Engine Size: 318
Refrigerant Type: 134a
Ambient Temp: 90
Pressure High: ~
Country of Origin: United States
I've done a lot of looking and seem to have found some possilby contradicting advice.
I have replaced the compressor in my truck.
While I have heard it can be done both ways, the majority of the directions I have read say that the best way to add oil to the compressor (which I'll call Method "A") is to remove the oil from the old compressor and measure it, then remove all of the oil from the new compressor, and replace with the same amount that was in your old compressor, either by adding it in the suction port, or right into the drain plug. Then you install the compressor, vacuum, and charge.
The other method (Method "B") I'm aware of would be to drain all of the oil out of the new compressor, install it, vacuum the system and then add it through the suction port while the system is under vacuum.
Since I've read about more people using Method A, and since the oil in my new compressor was the correct kind and was fresh and new, I decided to go with Method A.
I got finished with everything and it's running wonderfully and blowing cool and was happy as a pig in you know what, that I fired of an e-mail to the seller of the compressor saying what I had done and thanking him and what not. He sent me back an urgent message telling me to make sure that since I vacuumed the system that I would have to readd the total amount of oil into the system.
I replied back to him that I don't think the oil comes out, or at least not very much of it during the vacuuming process, and that I had no evidence of it coming out (oil running out of the exhaust of my 3cfm pump?)... He then replied back and said he wasn't sure then and that I should seek an expert opinion before continuing. Which I wholly agree with!
Can anyone tell me if vacuuming the system for ~45 mins with a 3cfm pump removes all / much / any of the oil to a degree that I would have to replace it?
Good question - I will be going through the exact same scenario shortly.
When I had my system evacuated I did notice that the machine pulled the vacuum then at the very end of the cycle it said evacuating oil. What I don't know is if the machine started doing something different at that point.
Under normal charging scenarios, no oil will be removed from the system, takes a very long time to boil off oil...you're safe with either method A or B.. Just make sure there is oil in the compressor, as you don't want to start it dry..
Freedoms just another word for nothing left to lose
After reading through about 25 pages of threads about "oil", I guess I figured out that the A/C vacuum doesn't create a "complete" vacuum rather it takes it down to 29.something inches which is enough to lower the boiling point of water so that it turns into a gas, and then all of the gas / air is vacuumed out, leaving the oil, which has not boiled off remaining in the system.
However, it is still very reassuring to hear somebody say that it didn't come out.
There is a "drain" mode on recovery/charge stations(Robinair) that occasionally works. The times I hooked up a Robinair RRR station to my cars, I don't even see the waste bottle fill up any more than it was.
Edited: Fri July 23, 2010 at 12:07 AM by nthach
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