Cold stuff

R134 Conversion

Burrr, it's sure cold here! - Pee Wee Herman, 1982, HBO


Last year I promised myself I would get my air conditioning switched over to the R-134a. I, like many old Rover owners, have the old "gooder", less environment friendly, R-12 in their systems. That stuff is now literally worth it's weight in gold. Last year's final charge up was $90(US). Plus the shop fee. The shop I had it done at is now defunked and the owners and operators were sued by no less than 20 former customers for some serious violations which brought the District Attorney and several State agencies knocking at their door, my favorite of course was tax evasion. Nice folks, not!
They suggested I put some leak finder in and I found out my compressor was leaking around the front seal. It turned a lovely color of green much like copper when it is exposed to the elements. The four basic components are the compressor, dryer, condenser, and the expansion valve. When you switch to R-134a you replace the dryer and normally the expansion valve. You also drain the oil and replace it with R-134a compliant oil, somewhere around 7 or 8 ounces.
So I have a leaky compressor, an old expansion valve and need a new dryer. I started looking around for a good price and to try and give the local guy a shot at my business as I always do. It's worth it to me to pay a little more if a local guy is employing local people with the money. Auto Air Oklahoma was very helpful and had the compressor, which is a Sanden 709 model. They could match the dryer if they had it in front of them. Expansion valve is priced nicely at Motorcars, LTD.
The goal of Sunday's air conditioning experiment was to get JagGuy's Range Rover A/C and Rogers's (Rogers, plural possesive) A/C working too. JagGuy had all the parts for his and we were to remove the dryer from my Rover and then I was to get it matched. I had decided I needed a new compressor due to the leak. We started with JagGuy's and found that the solvent to clean out the oil did not go into his hoses very well. We continued and tried to flush the system. We installed his dryer and evacuated the system. We waited the requisite 30 minutes to make sure the vacuum held, which it did nicely. JagGuy had done some checking around and basically understood everything we were doing so I went along with everything.
Turns out his expansion valve is bad and that is why the solvent didn't go in to his system very well. So no A/C without replacing the expansion valve. If you were not aware of it, the expansion valve is buried under the dash like a tick behind the ear of a very annoyed grizzly bear and almost as fun to pull. So JagGuy punted and we started working on mine.
JagGuy noticed the leak and said, "Why don't you try and tighten the bolts and see if they move." I said okie-dokie and wow they did move. I got a good 1/6 of a turn on each one. Well if the leak was due to the seal just needing some tightening then maybe the compressor didn't need to be replaced. We decided to gamble a bit and called O'Reilly's for a dryer. Of course they didn't have one according to the computer. JagGuy said these things are all really similar so we went down there to match it against what they had on the shelf. First try we got one that was identical. So we stocked up on some more R-134a with leak stopper and headed back to the shop. We pulled the compressor and added the oil. There is a handy drain plug on the bottom that worked great. I put 8 ounces in and put it back on the truck. There is a trick with the bolts to make it easier to install, just swap them in which ever way they go in easiest.
We flushed the system with the solvent. This time the solvent went in very easily and out just as easily. So that was a good clue to JagGuy's stuck expansion valve problem. We connected the hoses up and evacuated the system. We attempted to put the coolant in but it didn't take any. We were stumped. Then we removed the hoses and noticed a valve on the bottom of each valve that was closed. Wow the last guy who put in coolant actually closed the valves! Well we evacuted the system again and then added the coolant.
We decided that if the expansion valve was a problem we would only be out a few cans of coolant. We fired her up and started the A/C. I have a handy-dandy thermometer in the truck that has a remote sensor. I normally have it run to the driver's side just above the door. I took the outside sensor out of there and set it in the vent to measure the temp of the air coming out. We got 54 degrees F at a stand still. Well that was pretty good we figured and decided to go with it. I mentioned that I had seen 45 degree air when the system was on R-12 so we thought with the differences in coolant and no major modification we would see if that would be good enough. I headed home as it was getting late. On the drive home the temp of the air dropped to 39 degrees at highway speeds. The outside air temperature was in the low 80s. Wow that's great! I can live with that.
The next day I ran the A/C with the temp outside in the lower 90s. I got 50 degree air with town driving, basically nothing over 40mph. On the way home at highway speeds and 90s outside I got 47 degrees again. I am declaring the A/C repair a success, offically.
The Results. The difficulty of this project is a 3 on the Difficulty Scale. I would say this is a 5 if you don't have an air compressor or an excellent idea of how the system works. You also need a groovy A/C gauge set and a collection of "O" rings. The most difficult part was getting the coolant back in, in the appropriate manner and amount. Too much can cause you trouble and too little and it will not cool. I believe we used 2 and a half cans of coolant. JagGuy did his homework on the oil amount too and had purchased the oil prior to our repair attempt.
Will this work for you? I have to say we were gambling that everything in the system was working. It was a lucky break that the compressor just needed a little wrenching. And that the expansion valve works "well enough" with the R-134a coolant. I was prepared to drop $300(US) on this project and spent a little over $40 with it all said and done. So as long as it works I'm real happy and so is my pocketbook.
I owe JagGuy a big thanks and Rogers too for letting us use his garage. I still owe JagGuy for some of the solvent which works amazingly well on oil and grime on the outside of the hoses too, and a few bucks for the parts we stole from his failed system to make mine work. So as the kid from Alaska wrote to Pee Wee on the show, "Brrrr. It's sure cold here."


If you want to read more about AC repair I replaced my compressor and I talk about that on this page AC Compressor Swap.