R4 Oil Charge Difficulty

Commuter's Car on Wed July 02, 2014 9:25 AM

Country of Origin: United States

Greetings

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?

Thanks

mk378 on Wed July 02, 2014 10:05 AM

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.

Commuter's Car on Wed July 02, 2014 12:15 PM

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?

wptski on Wed July 02, 2014 12:26 PM

Quote
Originally posted by: Commuter's Car
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?
Not an R4 but I installed a new double lipped seal and gaskets in my backup vehicle last summer but only used it once after that. I was greeted this spring with a puddle of refrigerant oil under the compressor.

I didn't have a nitrogen setup last year but do now. It held 150psi for days and has held vacuum for over a week now. You'd think, how could have that leaked? But it did! Getting ready to charge it up any day now and try again. Have since read that it's common for new seals to leak before they have 8-10 hours of run time.

Edited: Wed July 02, 2014 at 12:27 PM by wptski

Commuter's Car on Wed July 02, 2014 12:54 PM

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.

Cussboy on Wed July 02, 2014 2:25 PM

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.

wptski on Wed July 02, 2014 2:35 PM

Quote
Originally posted by: Commuter's Car
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.
By looking at it from the bottom, it looked like it. Regardless it leaked but passes pressure and vacuum tests with flying colors.

Neither did till I found an old post here by someone that should know. I posted with links to the old post and author but it seems that they haven't been around this year so far.