Country of Origin: United States
I joined this forum to discuss automotive AC systems with knowledgeable people. I am an advanced amuture on this subject. I've been working on cars for the better part of 5 decades and AC systems for 15 years. I have professional grade gages and a Snap-On R-12 recovery unit and a fair supply of R-12. I am preparing to charge two cars that have a R4 with R-12. One has an orifice tube the other a TXV
What I am writing about today is getting the correct oil charge into R4 compressors. When I follow the instructions, it can be difficult to get the correct charge. I have always WAGed it by guessing the right amount. I have an idea that seems reasonable but I want to run it pass others.
This is what I am thinking: Put in the correct amount of oil into the compressor. Jumper the pressure switch so that the clutch will engage. Open up the return (low side) at one of the fittings. Route the hose that is toward the evaporator in to a can to catch the oil. Start the engine. Slowly pour oil into the the hose that is toward the compressor. Keep doing this until oil is flowing into the can.
The difficulty is knowing how much oil flow is the right amount.
Do you thing this will work?
That isn't going to work. Spinning the compressor how you would blow most all of the oil out of it when flushing the system (never put solvent into a compressor) to replace the oil. So you will be left with basically a dry compressor with that process. Spinning at engine speed with no refrigerant is also prone to cause damage. The R4 is a remarkably lousy piece of kit that must not even be looked at sideways if you hope for it to last.
With the lines open, pour in oil anywhere it will fit (preferably the compressor) to totak up to the rated complete system oil charge. If you have not flushed the other parts you are always WAG on the amount of oil in the car in any case.
Before charging a car with R-12, always conduct a static pressure test with some other gas first to be reasonably sure there are no leaks.
Thanks for your response
If I understand you correctly, it is best to flush so that all the oil is removed and then the correct amount can be added? The lines and oil are clean so I thought that I could avoid flushing. My main concern about flushing is getting all the solvent out when I am done. How much air does it take to get all the solvent out?
It is my understanding that the problem with the R4 is that the shaft seal leaks. When it leaks refrigerant it takes oil with it. After several recharges, there is not enough oil to lubricate the compressor causing it to fail. Is this right? Does the double lipped seal solve this problem?
I did pressurize the system to 120 PSI with air. It lost about 1 PSI an hour. I don't know if the test gages are leaking, the system is leaking or if it is Boyles Law. I can spray all the joints that I can access and look for bubbles but that will not work for the shaft seal which is, in my experience, the most likely place to leak. Is there any to test for a leak without pulling the clutch off?
You know that it is leaking at the shaft? The V5's tend to leak from the o-ring joints that seal the housing. When I replaced the shaft seal on one it passed the pressure test but started to leak at the housing as it was running.
Never heard of a break-in for a seal.
R4 is known to leak at the housing, called belly leakers. The R4 compressors on Mrs. Cusser's vehicles typically lasted only a few years (one SUV was R-12, the next R134a), likely worse because they were dual-air systems.
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