Many Turbo Coupe owners who would think nothing of installing a new clutch assembly or a timing belt and its components balk at the task of servicing their air conditioning systems. Perhaps it has to do with the unfamiliar properties of A/C refrigerants and its inherent dangers. The good news is that with some common sense and careful preparation it should not be any more difficult—and in fact, far less so—than most other work.
This article will explain how to convert older R-12 systems to R-134a—what parts and supplies are needed and how it’s done. While it is true that R-134a might not provide the same level of cooling power of its predecessor (more on this later)—in the end result with my car, any such differences aren’t worth discussing.
My system has worked flawlessly since January 2015, which as of this writing has been more than 5 years. I live in Phoenix AZ, which regularly experiences summertime temperatures in the high 110s—even occasionally 120s. Despite this, there has not been a day when I had less than comfortable air conditioned cool air in my Turbo Coupe (although admittedly it might have taken a few minutes in that heat to cool the interior down enough to get there). On Monsoon days—the rainy season with unexpected thunderstorms we have here in July and August—the high humidity was not a factor. And, in fact, the A/C was much cooler in my car than either of the two cars my wife has owned—a 2006 Chrysler PT Cruiser or her current vehicle, a 1997 Toyota 4Runner.
And in all of that time, I have never had to add ANY additional R-134a refrigerant. Some sources I read said that, because it has smaller molecules than R-12, the R-134a will eventually leak out—the solution is to add more refrigerant. I have not seen that to be true.
The procedures I will share with you are the same I used to achieve this performance. While I can’t guarantee that you’ll have the same experiences, it’s a great place to start.
In October 2014 my existing HR980 compressor seized, making it useless. Therefore, after years of struggling with air conditioning issues regarding repair and compressor replacement and paying someone else to fix it, I decided to take on the challenge of the conversion. R-12 is no longer legally available without a license, so it seemed like a great time to make the switch.
I did a lot of reading and research on the subject and sought the advice of several air conditioning professionals (see below). Much of the information I received, as well as my personal experiences, form the basis of this post.
I’d strongly advise finding at least one experienced professional to answer questions and provide information. Vaughn at Air Components in Mesa, AZ is one such person. His overall help was invaluable with this project. More on that company’s assistance later on.
This project ran from October 2014 to February 2015. Why did it take so long? There were several reasons: I had only a small amount of time available on the weekends to work on it; also, parts had to be researched and located—and there were a lot of dead ends. (In fact, the availability of parts that actually fit is probably going to be one of, if not the biggest issue you’re going to run up against.) And, the failure of a minor part during the vacuum-down operation slowed the progress considerably.
To be clear: the only parts you’ll need to make the conversion—unless you find something that is damaged—is the Accumulator, the Liquid Line (with Orifice Tube), and new green R-134a O-rings. Ford has said that the Tecumseh HR980 compressor is compatible with R-134a, and I can vouch for that, as mine has been running cold since 2015. Since my compressor had seized up, though, I obviously needed another one—the HR980 is not serviceable, other than a/c seals found within the unit’s “snout”. And, once the unit locks up, there is an excellent chance that the system will be filled with debris and contamination from the damaged compressor, and that has to be flushed out.
There was a split consensus online about replacing the Orifice Tube (within the Liquid Line) for a new one. My feeling is, why not? It costs less than $30, and it eliminates any guesswork. But—again, to be clear—if there is even the slightest chance of contamination in the system, it must be replaced.
Regardless if the compressor is seized or not, nearly every source I found had advised that the conversion to R-134a required the system to be flushed. One reason given was to remove all traces of the old oil, as it was found to be incompatible with R-134a.
(In a separate later post I will discuss the parts and tools required to service the seals and related components found in the HR980. While this compressor is basically a throw-away—and only used second-hand ones will likely be available as replacements—why not refurbish that one so it is as close to new in that regard as possible? I have two HR980s on my storage shelf—I have replaced the seals and related parts in both, vacuumed them out and sealed them up, vacuum intact, so the oil doesn’t oxidize and deteriorate.)
Here is a drawing that will help identify the various parts, and provide explanations:
To understand how to convert to R-134a, it’s perhaps best to understand how an air conditioning (refrigerated) system inside a vehicle works. You can get a pretty good idea of that by studying the drawing above; here’s an quick explanation of a/c theory.
Refrigerants like R-134a or R-12 have a very low boiling point—i.e. when the liquid turns into a gas. It’s this characteristic that forms the basis of a refrigerated system—your car and home a/c, refrigerator or freezer. While there are important differences in those home appliances, basically in all systems a fan causes cold air to circulate in an enclosed area by blowing air over cold refrigerant lines. Having now changed from a liquid to a gas after giving up its cold and reaching its boiling point (for R-134a that’s -15 degrees Fahrenheit), the refrigerant is pumped through the system, eventually passing through coils (or, in the case of a vehicle, a Condenser or small radiator-like component), which cools down the refrigerant to a liquid…and the process repeats anew.
The following is a list of components, tools and supplies you will require for this project.
ACCUMULATOR. Also known as a Receiver/Drier. Filled with a special drying desiccant, its primary purpose is to remove moisture—condensation—from the R-134a. Water vapor works in a way that is contrary to the operation of the refrigerant, and can cause rust and oxidation to internal parts, so it is vital that as much as possible is removed.
The particular Accumulator model for Turbo Coupes (and Fox Body Thunderbirds in general) was discontinued long ago. There are many similar items that will require at least some degree of adaptation and/or modification. The replacement I discovered will be discussed later on.
The LIQUID LINE is an aluminum and neoprene piece of tubing that contains the Orifice Tube, whose purpose is to help convert the R-134a gas back into a liquid under pressure, by restricting the refrigerant as it passes through.
Remember that if the HR980 Compressor has failed in some way—most likely by seizing—the Orifice Tube MUST be replaced.
It is possible to purchase only the Orifice Tube—cutting the Liquid Line, replacing the Orifice Tube and then repairing the Line. There are kits sold for that purpose…but in my experience it’s just easier in the long run to get a complete Liquid Line with the Tube already enclosed than to muck around with all that. (The cost is about the same, by the time you buy the Kit and the new Orifice Tube.) Perhaps in the future we won’t have the Liquid Line available any more—only the Orifice Tube—and we’ll have to go ahead with that repair. For now I prefer the easy way.
O-RINGS: The existing O-rings have to be replaced, as they are not compatible with R-134a and it will cause them to deteriorate over time, I was told. New light green O-rings are inexpensive and readily available; I have a small stockpile I’ve collected over the years. And, consider getting some garter springs for the couplers as well, in case yours are rusted or contaminated by grease, oil and/or dirt. There is no difference between R-12 and R-134a springs.
I make a habit to replace the garter springs on my car every time service is performed—I also clean out the groove in the coupler’s channel with carb cleaner to make certain of a good seal.
NAPA’s part numbers for the various R-134a O-rings (there are 3 sizes) are 407006, 407008, 407010; there are 4 each. Get some extras just in case. The new Accumulator and new Liquid Line should already include suitable O-rings.
A/C MANIFOLD GAUGES. You can spend $200 and up for these. My advice: unless you have a repair shop and you service a lot of air conditioning problems on a regular basis, and you need an absolute guarantee of reliability, get the set from Harbor Freight for about $60. (For the $200 price of the professional set, you could purchase almost 4 from Harbor Freight.) I’ve had mine since December 2014 and have had no problems. I’ve diagnosed several cars with them, and my next-door neighbor has borrowed and used them as well. Simple and easy to use. In fact—maybe you should have these regardless.
Word of advice: read the instructions THOROUGHLY, handle and get to know them a bit before use. Attach the High- and Low-Side couplings to the ones on the hoses. Get used to the differences, in that the couplings for the fittings close COUNTERCLOCKWISE, while the manifold valves close CLOCKWISE. This is important.
VACUUM PUMP. Just under $100 at Harbor Freight. The one I got in December 2014 still runs as it should. Be sure to use the 20% online coupon at harborfreight.com; just visit that site on your phone and have them scan the barcode found there.
Whilst there you might want to consider a bottle of Air Tool/Compressor Oil. When vacuuming down the system, any moisture or leftover flushing material will quickly contaminate the Pump’s oil. (There is a sight glass and you can see the stuff running through it.) It’s a good idea to change it after such a session, as that oil is vital to the Pump’s operation. A bottle costs about $8.
R-134a CAN ADAPTER. This screws onto the can of R-134a; when ready to charge the system, simply turn down the valve, which pierces the can, and re-open. This valve is connected to the Yellow center hose of the gauges—to begin filling the system you just open the Yellow valve on the Manifold Gauges. More on this later. A bonus feature of this tool is it allows you to use just part of a can and store the rest. Should be available most anywhere that sells a/c parts.
R-134A. WITHOUT compressor oil—better to measure and add your own (you’ll be draining the oil from the compressor, measuring it, and putting in that fresh amount).
COMPRESSOR OIL. This has to be SPECIFICALLY for R-134a AND ESTER-based. The oil shown in the above photo is what you want. The smaller bottle is about $10. Don’t buy too much at once as, like brake fluid, it reacts with air and will become oxidized.
SYSTEM FLUSH. You’re only flushing the Evaporator, Condenser and the High- and Low-pressure lines. DO NOT FLUSH THE HR-980 COMPRESSOR! You’re going to be replacing the Liquid Line and the Accumulator, no need to flush those. Two 17 oz cans is good, at least to start. This is what I used:
ADAPTERS, R-12 to R-134a. The R-134a fittings are bigger than the R-12 ones and screw right on to them. BE WARNED that some are designed not to be removed once installed. This is to prevent you from going back to R-12, I guess.
I had—shall we say—an interesting adventure with one that I’ll share, so you won’t experience it.
SPRING LOCK COUPLING/DECOUPLING TOOLS. These are color-coded plastic sleeves that are spring-loaded and have a lip inside, which will allow the A/C coupling to be disconnected. They look like this:
LARGE METAL COFFEE CAN. My experience has shown this to be an ideal container to drain the oil from the compressor into. Make sure it’s clean, then simply turn the compressor upside down on it. It will fit perfectly on top with no boards or paint sticks required to hold it upright.
LARGE SPAGHETTI SAUCE OR PICKLE JAR, with LID. This is to catch the Flush and junk that comes out of the Condenser and Evaporator.
SPRAY GUN FITTING. A metal fitting with a rubber tip—attach this to the flexible hose coming out of your air compressor or air tank. This is to “flush out the flush” from the Condenser and Evaporator.
GRADUATED CYLINDER. These are available online from Amazon and others for about $10 for a set of four. You could use a measuring cup, as long as it has 1 oz/1ml markings, to accurately measure the compressor oil.
STEEL DOG GROOMING COMB. Plastic ones won’t work. You don’t necessarily need a new one—check at secondhand stores and yard sales. Just be certain that its teeth are undamaged and straight, and none are missing. This is used to comb out the fins of the Condenser (and the Evaporator, if you’ve removed it).
LARGE PLASTIC BOWL. It should be big enough to hold warm water and the R-134a can. This helps keep the can’s contents warm, which will help the refrigerant flow better and faster into the system as you recharge it.
Now that we have assembled all that we need to complete this project, let’s get started.
First, the obligatory warning: DO NOT DISCHARGE R-12 REFRIGERANT INTO THE ATMOSPHERE! Remember that R-12 will do serious damage to the upper atmosphere—even if you don’t believe in all that, IT IS ILLEGAL, and if you are caught, there is a HEFTY fine. Of course, in most cases if your system has failed, you probably don’t have any left anyway.
It is possible to hook up the Vacuum Pump in such a way that you could evacuate the system into a small metal compressed air tank. You’d then visit a local a/c shop and have that tank evacuated. Years ago before I possessed the required tools and knowledge I frequented a shop that would evacuate the system—I would purchase the replacement parts as needed and install them, and they would then vacuum out the system and recharge it with my recovered R12, plus whatever more I required. This service cost $250, as opposed to the $750 it would have cost to have them do all that.
The first thing you’ll want to do after evacuating the system is to get your coupling tools and begin the process of removing components. It’s likely been a while since these couplings have been apart. Be careful not to damage any nearby parts with your hands and arms (and yourself) if the coupling suddenly releases; that’s the nightmare of creating more repair work accidentally. Look at what’s nearby and cover any parts that might get struck with some padding, like old rags.
You will be able to feel the lip of the tool enter the spring cage. Once you feel that, start to pull the other line away.
Work carefully and be patient! If you don’t seem to be getting anywhere, consider using a medicine dropper and adding some of the Ester oil to the spring cages—allow a few minutes for that to work. If there’s still no luck, try spraying some PB Blaster in there—tap the compression joint LIGHTLY to set up vibration, that helps the ‘Blaster work. Just make sure to clean the fitting parts afterwards with Brake Cleaner to avoid contaminating the system.
Once you’ve gotten it all apart, study and evaluate everything to check for hidden or obvious damage. Carefully note areas near the couplings for oily black dirt—this is usually an indication of refrigerant leaking from the system and bringing with it some of its oil, which will attract dirt. While this in itself isn’t always bad news—I’ve had that same black dirt residue on my couplings for years, and have no noticeable loss of R-134a—it is worth noting. As with most repairs, it’s a very good idea to write down notes and take pictures as you go.
Be especially careful of removing the couplings from the Evaporator. Many times the tubes are not secured as well to the component as they should be, and if you pull one out of its housing it will, as the saying goes, spoil your day. (You’re now looking at pulling the dashboard out to get to the heater box and the damaged Evaporator. Ugh.)
Unbolt and remove the HR980 compressor and the Accumulator. Use care not to tip the Compressor downwards and allow oil to escape—you’ll need to measure it later on. Turn it upside-down on the Large Coffee Can and let it sit overnight. From time to time, turn the pulley to spin its innards (unless it has seized), this helps the old oil drain out. If it has seized—pick it up, turn it fittings-side up, and set it back upside-down, as an aid in draining the oil. Do this step as many times as it takes to get the oil out of there.
I chose to remove the Condenser—the smaller radiator-like component in front of the radiator—in order to better flush it out and later add the Ester oil…but mostly, to clean all the dead moths/bugs/leaves/etc. out of its cooling fins, and to comb them out. Doing that makes this arguably the most important item in the system that you have some control over. You can remove it without too much fuss by taking off the upper radiator supports and maneuvering the radiator a bit toward the engine.
Plug the entry and exit lines to prevent moisture from entering the system, then carefully spray the front and back of the Condenser with a garden hose to get all that old crap out of there. A soft toothbrush or similar item—and some dish detergent or mild degreaser—will help with the stubborn junk, but be careful with any wire brush activity. This is an aluminum component, and you don’t want to cause any damage to the softer metal.
When you’re satisfied with the results, use the Steel Dog Grooming Comb to work on the fins. Likely, many are bent, some very badly. Work slowly and carefully to get them back to acceptable condition. A small flat-bladed screwdriver—or, better yet, a SPUDGER (a black plastic tool that has a point on one end and a flat blade on the other) can be a big help (the plastic is less likely to damage anything). Be especially careful that you don’t accidentally pierce the refrigerant tube behind the fins, or you’ll be shopping for another Condenser. Remember that the more air you can get flowing through the fins and over the refrigerant tubes, the better cooling experience you’re going to have. When it’s done set it aside, preferably in a warm spot such as in sunlight to dry.
A note on cleaning in general: Because I think it’s unprofessional to re-install dirty parts, whenever possible I thoroughly clean all the parts, especially those that are going back on. Dirty parts usually can’t be cleaned as well after they’re installed; it’s also harder to spot damaged or worn areas on something that’s obscured by dirt. And, since the system’s oil attracts dirt, that gunk could be hiding a split or hole.
FLUSHING THE SYSTEM
Once everything has been cleaned and examined, it’s time to start the flushing process. The lines—the Suction, which is a 5/8” line; and the Discharge, which is a 1/2” line, will be easy—if you have a can of Flush like in the photo above, just press the hose’s pointed nozzle onto one of the ends, hold the other—pointed away from you—and press the top button. A few sprays should do it—DO NOT breathe in the mist or stuff that comes out. It WILL be nasty and smelly. It will probably only require a quarter of the first can of Flush, if that. Now, get the air line with the blow gun nozzle that you set up before and blow out the lines, to get all that junk out of there. When you vacuum the system what is left over will be pulled out, but it’s always better to get it as clean as possible before that.
Remember NOT to waste flushing agent by trying to flush out the Liquid Line, the Accumulator or the Compressor.
Put an old piece of hose on the Intake side of the Evaporator (see drawing above) and Condenser (ditto). Punch two holes in the metal lid of the Sauce or Pickle Jar (one big enough to stick the hose into), stretch a piece of thin material like part of an old t-shirt over the top. Screw the lid on the jar, punch a hole in the rag, and stick the other end of the hose through those holes. Put the rubber tip that’s on the end of the Flush hose against the open end of the component and spray liberally into it. Keep an eye on the stuff that’s going into the jar—it will, as the saying goes, mess you up. DON’T breathe it in—the rag is covering the jar so you’re not directly exposed to it. Remember that despite the overall size (especially of the Condenser), there is a connected network of small tubes inside, so you should be able to do a complete flush using about 1/2 to 3/4 of a can for the Condenser and 1/4 to 1/2 for the Evaporator. After a few applications, switch the hose to the Exhaust side and spray a couple more times. Now, remove the hose, turn the open ends away from you. Get the air line with the spray gun/rubber tip, hold it against one of those open ends and spray; then switch to the other open end. Flush out the components thoroughly, until clean air comes out.
Yeah, all that nasty junk was in there. Makes you wonder how it worked at all.
DO NOT USE WATER! We will be trying to get any water and water vapor OUT of the system later on, when we Vacuum it—so DON’T add more.
Remove all the old O-rings—a metal pick works well with for this. Group them by part, so you can easily compare the new ones for replacement.
Plug all the openings in the lines; if necessary put plastic wrap and rubber bands over the openings, if you don’t have suitable plugs. The goal is to keep moisture from the air out of the parts, now that they’ve been flushed.
Remove the compressor from the coffee can and pour the oil into the graduated cylinder. This will take a bit of doing, as the metal lip makes it difficult to pour the oil directly. Keep working with it until you’ve got as much of the oil as you can out of the can and into the cylinder. Write down the amount in your notes—you can then discard the oil.
Now that you know how much was in there, put some fresh oil back in and slosh it around, spin the compressor shaft/pulley to help spread it around. Since we can’t put Flush in there, we need to flush it out with fresh oil.
This step is particularly important if it’s a replacement for a seized one, because you don’t know how well the system it came from was maintained.
Try and get as much of the dirt and contaminants out of there as possible. This will take some time and effort. Drain it back into the coffee can by putting it back on top—after a few minutes pick it up, add some fresh oil, slosh it around, and put it back. Repeat until no more yellowish smelly oil and/or dirt comes out. (You might have to do this many times.) Plug these connectors as well when you’re done.
I did not measure the oil in my Compressor—I figured that since it was seized, it might not be accurate. I now think that was a mistake—it would have been better to obtain those results, even if I later disregarded them. (You can’t utilize results you never bothered to get.) Doing some research, I found that the proper Ester oil distribution is: 4 oz to Compressor; 2 oz to Condenser; 2 oz to Evaporator, for a total of 8 oz. in the system. This is what I used and have had no issues.
The proper amount of oil is very important. Too much oil and it will pool in the lines and components, reducing the cooling capacity; too little and it could burn up the compressor. Since the system’s correct amount is 8 oz., if you had 5 oz in the Compressor, divide up the remaining 3 oz between the Condenser and the Evaporator. Ditto if you had 3 oz in there, divide up the remaining 5 oz.
Much of what I read discussed pouring the oil into the Condenser and Evaporator and tilting those components up, down and all around in such a way as to better distribute the oil in there. Since I did not remove the Evaporator, that was not an option. Instead, I put a hose on the end of a funnel, stuck the hose in one of the open tubes in each unit and just poured the measured amount in. Then, I plugged the open line and used the air line with spray gun in short light bursts to move the oil around a bit. I kept checking the plugged end and when I saw oil there, I stopped.
I did try and spread the oil evenly around in the Condenser before plugging the lines again and reinstalling it into the car.
When all the oil is in place and spread out reasonably well, it’s time to put it all back together. Start with the Suction and Discharge lines—smear some ester oil on the ends where the grooves for the O-rings are and carefully install the new green ones, matching them up size-wise with the older R-12 ones. Be careful not to twist or kink them as they’re installed. Get some oil on anything that already HAS O-rings, like the new Liquid Line and Accumulator.
If you purchased new garter springs, remove and discard the old and replace with the new.
Install the Compressor and Accumulator in their locations, and begin the process of connecting all the parts together. You should feel a satisfying CLICK when the connectors fit together and are seated.
My Accumulator, as I mentioned before, was not an exact replacement for the older one.
Vaughn informed me that the original part number for the Accumulator was 207-517, by a company called Frigette, and that it had since gone out of business. So I knew I was facing a likely uphill battle to replace it—from what I had researched online myself.
The accumulator I finally found and installed is part # 60-4520, by Murray Climate Control. Parts Counterperson Mari from an O’Reilly’s Auto Parts in Mesa AZ spent almost an hour searching through old parts manuals—and the store’s existing stock—for an accumulator that was very similar to the old OEM one that I brought in. (That’s great customer service.) What I got was the closest that was available.
But, it wasn’t the correct one, just the closest that they had. The Vapor Line (the 180 degree line shown in the above photo) was too short, so there was a gap between the Accumulator and the Condenser.
I had just been to Air Components hours before—they have a machine shop that is able to create or adapt parts. It occurred to me that I could ask them to fashion a metal adapter which would properly connect the Accumulator to the Evaporator core. Below is what it looks like, and my completed Accumulator setup.
This fixed the Accumulator issue, and it offered the additional benefit of solving it for years to come, as long as this particular Accumulator is available (NOTE TO SELF: Buy another Accumulator while you still can).
I saw that the HR980 compressor I had kept in storage as a replacement had a cracked ceramic outer seal, and I did not trust it to hold up under the refrigerant’s high pressure. I had to find an inexpensive replacement. (The prices on these are outrageous for a 30-year-old used high-stressed part with no warranty—expect to pay upwards from $100 on an auction site like eBay.)
As it happened, miraculously I found one on eBay the Wednesday evening before Thanksgiving in nearby Tempe for only $10! I met the seller on the morning of Black Friday and it was mine. As it turned out, I came to doubt its functionality due to another failed part (and due to no fault of its own, as I later learned). It didn’t look like it was doing its job properly in pulling the R-134a from the can during recharging, which was an incorrect assumption. I felt like I had no choice but to locate yet another. (The $10 one has been reconditioned and is in storage as a future replacement).
The final step in this Reassembly process is to install the R-134a Fittings. As mentioned, some have barbs in the threads to prevent removal. They just screw on to the R-12 ones—to be safe and if possible, I would use Teflon tape. The High side fitting, near the Compressor, is a bit larger than the Low side one, found on the Accumulator. Also, the High side’s protective cap is RED; the Low side cap is BLUE. This is a help in attaching the fittings from the Manifold Gauge Set. You cannot mix the two, mine were not physically interchangeable. It’s a good idea to examine them carefully first—you’ll see why later.
VACUUMING AND RECHARGING THE SYSTEM
Now comes the fun part. For this part, you really do little more than watch.
Hang your Manifold Gauges on the hood striker plate (the piece that extends downward into the hood release), or in one of the holes found on the hood’s inner surface. Recall that the arrangement of the attaching hoses include a Blue Low side hose, a Red High side hose, and a Yellow Vacuum/Charging hose. There are also Blue and Red hose Coupling fittings. Inspect the seals inside the threaded fittings to be certain they are present, in good condition and not damaged.
Next, using slip joint pliers, tighten all the hose fittings on the hoses where they attach to the Gauge Set. There’s no need to “white knuckle” them, just tighten so they are secure. There could be vacuum leaks in your system, but you don’t want to tear everything apart looking for a leak when—it’s in one of those connections.
My experience has shown that it’s probably best to attach the Hose Couplings to the R-134a fittings first, then screw on the hoses, again tightening them with slip joint pliers, and not too tight. Remember to CLOSE the Coupling valves by turning them COUNTER-CLOCKWISE. Likewise, be certain that the Gauge valves are also CLOSED by turning them CLOCKWISE.
Get your Vacuum Pump ready and plug it in. I elevated mine on old milk crates so I could easily see the Sight Glass—watching it will tell you much about what is going on, at least initially, in your system as you vacuum it down. Get yourself a chair or stool to observe the pump’s activity. Turn it on first and get used to how it sounds when it’s running—that sound is a HUGE indicator as to what is going on—good and bad—in this process. It will sound somewhat different when it is actually connected to the system and is pulling vacuum.
Connect the Yellow Vacuum/Charging hose to the fitting on the Vacuum Pump. There are two brass fittings on Harbor Freight’s Pittsburgh 2.5 CFM Vacuum Pump…it doesn’t matter which you use, whichever is more convenient (I used the Side one). Tighten that fitting as you did the others.
Do NOT start the car at ANY time during the vacuuming process. Open the Valves on the Hose Couplings (CLOCKWISE). Inspect all your connections, and turn the pump ON—now open the Gauge side valves (COUNTERCLOCKWISE). The first thing you are likely to see is a lot of whitish smoke coming out of the vacuum pump. This is why you started the pump beforehand—assuming there were no problems at that time with its operation, what you are seeing is water vapor boiling and being pulled out of the system.
WATCH the Sight Glass. You will probably see brownish gunk circulate past it; this is any leftover Flushing material. The pump’s idling likely will change somewhat in volume and rhythm. So far, this is all normal.
Observe the Low side gauge—very soon if not right away that reading should drop way to the left, about -30 on the scale. THAT is what you want to see! It should remain there with little to no movement, or else something in the system is not seating properly. If that’s the case, listen for a whistling or hissing sound, characteristic of a vacuum leak. You should also wiggle and gently shake the various connections to see if that improves the situation. If the reason is not obvious, stop the pump and examine the various parts for the possible problem. You might have to disassemble parts and look for causes like torn or dislocated O-rings.
There are rarely any problems at this point, if you’ve been careful in following instructions and using good common sense.
I must admit, I was fascinated with the concept that water boils at room temperature when a vacuum is applied. I had a chart at the time that I relied on, relating elevation to the vacuum measurement of inches of mercury (in/Hg), and with ambient temperature—that I now cannot find.
The point is: when you reduce the ambient pressure to -30 in/Hg—water boils away, for the most part, depending on elevation and ambient temperature. There should not be ANY water vapor in the system. The purpose of vacuuming is 1) to seat the O-rings and be certain the system has no leaks; and 2) to remove ALL of the water vapor.
Now, have a seat. The longer you vacuum the system, the better—but it should be for at least 2 hours. You don’t have to sit with it and watch it all that time, but it’s a good idea to check on it periodically. After two hours (or whatever time after that you feel comfortable with), shut off the pump and close the Red and Blue Gauge valves (keep the Yellow one OPEN). Take a picture of the Low gauge with your phone, to record the reading. Now, let it sit—overnight is good. The longer you allow it to sit, the better, not just to check the airtightness of the system but also to boil out any remaining water. If you come back in a few hours and the needle seems to have moved a bit, take another photo and don’t panic. If the needle stays at its new reading, something might have settled and the system is stable now. If it moves AGAIN, it might be time to jiggle and gently shake the connections, and watch the needle. If it’s now stable, I would run the vacuum pump again for a while, shut it off again and check the reading.
Don’t fudge on this, or settle for less than satisfactory results: “I vacuumed it for 10 minutes and let it sit for 5, I’m ready to start charging now.” This could be a HUGE mistake. If you haven’t gotten all the water out of the system it will operate poorly; if there are leaks you’ll slowly lose refrigerant as it escapes, and air gets in. Bad idea. Most everything I have read—and my personal experience—says you need to vacuum the system for AT LEAST 2 hours. If you have replaced EVERY component with its brand new counterpart, then yes, that length of time might not be necessary. But even in that unlikely scenario, why not vacuum it for that long regardless?
Once you are satisfied with the steady vacuum in the system, the next step is to begin the recharging process. Remember that we want as little outside air—only R-134a—in the system as possible. By carefully following these steps, you should have little trouble.
Close the Yellow, Red and Blue valves on the Manifold Gauge Manifold set (if you haven’t already). This disconnects the system from the Vacuum Pump. You can now unplug the Pump, disconnect the Yellow line to it and set it aside.
Turn the T-handle of the R-134a Can Adapter COUNTER-clockwise so the sharp point is no longer visible, and screw this end onto the Yellow hose of the Manifold Gauge Set.
Fill up the Large Plastic Bowl about halfway with warm water; the can of R-134a will go in there as you charge the system. Locate it someplace like the top of the air filter for now.
There’s no sense in being unsafe. R-134a is very cold, and contact with your skin—especially your eyes—will be unpleasant, to say the least. I wore gloves and safety glasses. You only have one pair of eyes!
Thread the first R-134a can onto the Can Adapter. I like to smear a little grease on the threads to make it easier to attach and remove. Be sure to tighten it securely by hand.
Recall that the system has been closed to outside air all this time. We know how important that is—the only stuff that’s supposed to be in the system are Ester oil (and not all that much), and R-134a. We closed the Manifold Gauges, so the system should remain pure. Well, once we disconnected the Yellow line from the Vacuum Pump, guess what happened? Yup, it’s now full of outside air…we have to purge that out so it doesn’t enter the system.
Have your slip-joint pliers at the ready; you’re going to follow these steps in this order: first, turn the T-handle CLOCKWISE so that the sharp point pierces the top of the can, then turn it back open. Now, SLOWLY loosen the Yellow threaded line on the Manifold Gauges connection with the pliers so that R-134a leaks out. You should hear a hissing sound and both the connection AND the can should start to feel cold. You only need to bleed out a small amount of R-134a! After a few seconds, tighten the Yellow threaded line connection again. Now open the Blue and Red valves of the Manifold Gauges. You’re now charging the system. After a couple of cans, you’ll be starting the car and having the compressor pull the R-134a out.
Let the system empty the can—this is a natural result of its vacuum. You shouldn’t need the can to be in the warm water bowl at this point. Once the first can feels empty (it will be obvious—shake it a little to be certain), close all the Manifold Gauge valves (and the one on the Can Adapter), SLOWLY unthread the can from the Can Adapter and remove it. (BE CAREFUL! There could be a little pressure still in there.)
Attach the second can as before, purging the Yellow line again—re-open the Gauge valves and continue the re-charging process.
Eventually the system will stop accepting the R-134a. When this happens it’s time to start the car. BUT FIRST….
CLOSE THE HIGH SIDE (RED) MANIFOLD GAUGE VALVE! The importance of this CANNOT be overstated.
The compressor will soon raise the High Side pressure above 100 psi. This is easily enough to explode the R-134a can! You don’t need the HIgh Side valve open to charge the system. From now on, all charging will be done through the LOW side only. (As a safety precaution I also closed the Coupling Valve at the High Side connector as well.)
Start the car, and set the A/C controls to MAX. For standard units, this means the temperature slider should be all the way to the right, fan on HIGH. For EATC (Auto Temperature) systems, lower the temperature to 60 and make sure the system is set on AUTO.
The compressor should be cycling on and off—this will happen less and less as the system accepts the charge, depending on the ambient air temperature. You should see readings on both gauges. Those won’t mean much until you get to the third can.
Generally speaking, the Blue gauge should read (well) below 100, and the Red one around 100-150, again depending on the outside air temperature. If yours don’t look like this, is there gradually cooler air coming out of the vents? Shut off the car, stop and listen for any hissing or other odd sounds.
There are two schools of thought regarding getting the refrigerant into the system. Some will instruct you to turn the can upside-down—this is called LIQUID CHARGING. Generally speaking, you probably should not be doing this. There is a chance that you’ll overload the system and could cause some damage. The compressor is designed to compress GAS, not liquid. The better and safer alternative, therefore, is GAS charging—this is somewhat slower, but soaking the can in the warm water helps a bit.
When you get to the third can (probably around 15-20 minutes or less), spray the Condenser—the part in front of the radiator—with your garden hose or a spray bottle. Drench it pretty good. Two things will likely happen when you do this—the air coming out of the vents will get a little warmer, and the gauges’ readings will drop a bit. This is a necessary step for the proper exchange of heat, so the system gets the optimum amount of refrigerant.
The system is likely going to take 3-4 cans; probably 3 1/2. This isn’t like filling your gas tank. The system will keep accepting R-134a likely until you, frankly, blow something up. Obviously this is not the desired result. Since there is no “Full” indicator, we use the gauge readings, and the temperature of the air coming out of the vents, to estimate how full the system is.
R-134a, as we said before, is different than R-12. You shouldn’t chase after vent temps that you might have had with R-12—that could prove dangerous the next time your local climate reaches its highest temperature. I put a meat thermometer in my center vent louver and stopped when it hit the mid-50s. Here’s a few words on how the outside—ambient—air temperature is going to affect how you proceed.
First off, here is a formula that should be used as a guide when recharging the system, as the HIGH SIDE PRESSURE BALLPARK PSI: Ambient (Outside) Air Temperature x any value ranging between 2.2 to 2.5. So, if your outside air is 80 when you are recharging, that would be 176 (80 x 2.2), or as high as 200 (80 times 2.5). That’s the range you should be seeing on your High gauge. The Low pressure side’s reading is of less importance—except that it should be much less than the High side, obviously.
It’s important to remember that the High pressure side’s PSI will likely hit the upper 200s—or even 300—in July or August, so it’s important that you not overcharge it when it is cooler. Much of what I have read advised that the HR980 is not the most efficient or resilient compressor, and doesn’t like high pressures. I’ve not had any issues with mine, and as I said before, as of this writing I haven’t had to add any more R-134a since I first recharged it in early 2015.
(Here’s a handy conversion from Fahrenheit to Celsius, should you ever need it: C x 1.8 + 32 = F .)
I mentioned several times before about an issue I had with my recharging efforts. It illustrates very well, I think, the philosophical concept known as Occam’s Razor—which states that the simplest explanation or solution is often the most correct.
I was into the Flushing stage in the process when I hit a snag. Having had limited experience with the “start to finish” of this operation—I had not flushed out a system before, but had recharged several different vehicles—I was unfamiliar with what to expect. I began vacuuming the system, but something wasn’t quite right. I ran the Vacuum Pump for about 4-5 hours, and finally decided that this part was done, let it sit for several hours to see if it would hold, and it did. I followed the procedure to the charging part, but the system would not accept the charge—I got about a half a can in. I tried for 30 minutes to an hour. I started the car, nothing worked. I shook and shook the can, it would not go in. I shut it down and tried vacuuming it again. It held the vacuum fine, but there was still something wrong. It wasn’t going the way I thought it should, certainly not the way it had before with other vehicles. I left it overnight to make sure it wasn’t a vacuum issue.
So I started looking for the problem. It wasn’t losing vacuum, so it wasn’t a bad connection with any of the components. I had purchased a set of R-134a adapters for the R-12 fittings, and fortunately they were removable. I found no problem with the High side one; but when I removed the Low side one on the Accumulator I saw the problem right away.
As you can see by the above photo, the Schrader valve connector was damaged and was not allowing its release. As it turned out, it was that simple. Fortunately I had two A/C hoses on the $10 Compressor I had purchased, both had R-134a adapters. I removed the Low side one and installed it.
When I connected the Vacuum Pump again and turned it on, the results were IMMEDIATE. The Pump spewed out white smoke (water vapor) and all kinds of nasty brown gunk flowed across the sight glass. FINALLY the system was being vacuumed out properly! I let it vacuum down for about 3 hours, then allowed it to sit undisturbed for an hour or so to be certain it still held vacuum. All was good.
It emptied the first R-134a can in about 3 minutes. The rest of the process went equally well. So, what took an elapsed time of a day and a half—over several days, actually—was done and over with in less than an hour. Moral of the story: sometime’s it’s an obvious answer—don’t overlook the obvious.
Run the A/C for a while just to make sure all is okay. Once you are satisfied with the results, you’re done. Disconnect everything, clean it up and put it away, and open a cold one! A job well done.
In a later post I’ll describe how to service the internal seals and parts of the HR-980 compressor. It’s a worthwhile exercise, in that by doing so you might be able to avoid doing this again soon.