Engine Size: Cummins
Refrigerant Type: R-134
Ambient Temp: 90
Once PAG oil has been exposed to the atmosphere, does it all have to be flushed out and replaced?
The A/C on my Suburban has not been working for several years due to a massive leak in one of the hoses. It was converted to R-134 and most likely had PAG oil. From what I understand, PAG oil is highly hygroscopic so since it has been exposed to the atmosphere, the PAG oil left could be saturated with water. I've also read that putting a vacuum doesn't boil the moisture out of the oil, so it looks like I need to get all the PAG oil out of the system. I used a blow gun to apply pressure to the condenser but not much more than a couple of drops of oil came out. The oil that came out was clear with a greenish tint. How do I get all the oil out of the condenser without removing it which would be a huge job because the radiator also has to come out? I'm going to remove the compressor to get the oil of out of it and replace the dryer. Would there be any oil in the rear A/C that I need to deal with?
Will either ester or mineral oil boil off moisture when subjected to vacuum? If so, I would think it would be a huge advantage to use this type of oil in the circumstance of what I'm having to deal with.
Edited: Mon May 16, 2011 at 2:31 PM by edahall
If you have contaminated oil in the system. It's best to remove all of it.
The oil is old, it is hydroscopic, and how much is in there? The reason only a little blows out is because of the huge internal surface area and the oils ability to bind to these surfaces. Volume, velocity, and the right cleaning chemical is the key. Please read the attachment in my signature for a further understanding of what is involved in proper flushing.
It was suppose to have 11 oz of oil in the system. The system was converted to R134A 3 years ago with either PAG oil or Ester. Is there a way to tell the difference between PAG and Ester oil? I would like to put the same type of oil back in. Nothing was written down and PAG oil is what is usually sold during the conversion.
With no heavy particles floating around, can proper flushing be attained with the right chemicals and compressor with a blow blow gun attached?
A chemical analysis of an oil sample would possibly be the only way to know which oil is in there. This is where proper flushing can eliminate the many unknowns and get you to a clean and dry restart point.
As far as flushing with a blow gun... My professional opinion (did you read the info attached to my signature?) is that anything is possible; like sucking a swimming pool dry with a drinking straw.
Easy way to handle the condenser is to replace it with a new parallel flow type with an advantage of it being able to handle the additional heat load of R-134a for better interior cooling. The rest is fairly easy, accumulator also has to be pitched. Compressor is drained and flushed out with new oil.
Where is Chick at with his brake cleaner. I have been using NAPA paint lacquer thinner, because it is lacquer, not that crap they sell are hardware stores labeled lacquer thinner that is anything but lacquer.
LOL, why the bug to repair it this year, we had snow here last week and still using the heater. Been too damned cold to even think about AC, where is Gore at when you need him?
Nick, what is the part number for that thinner?
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