Drawing on my experimental lab experience, I can tell you that oil designed for vacuum pumps or compressors is designed to have what is called a low vapor pressure. Or in other words, as long as the pumping line is not filled with oil and only the volume above the oil is being pumped, then the molecules of the oil will not easily come free from the liquid due to the strong surface tension.

Now a substance with high vapor pressure would be something like acetone. Generally these are also the types of liquids that evaporate easily when on your skin making your skin feel cool.

 

UPDATE:

So I have not heard back from GPD but I have been doing some digging on my own. Here is what I have learned and what I have concluded:


According to the GM manual the "System Capacity" for oil in the AC system is the same that is listed on the side of the OE compressor; 8.0 oz.

The new replacement compressor (GPD 6512124) on its label says the oil amount is 6.4 oz.

According to downloads from TEAMEC and Sanden, the amount of oil supplied with their compressors is the amount that would be needed for the whole system. Hence, when replacing only the compressor, you put back into the new compressor only that amount that had been in the old compressor since the balance of the oil is distributed in the rest of the system. To keep the whole amount of oil in the new compressor would mean having more than enough oil in the system; the total amount shipped with the compressor plus any remaining oil in the other components.

My interpretation is that the capacity listed on the pumps is the same as the total amount of oil that should be in the system. Thus, having flushed out the parts I've kept and having replaced all the remaining components so that there is no oil left, I should put 6.4 oz of oil into the system by filling compressor with that amount of oil.

Thoughts?

Christine

 

UPDATE TO THE UPDATE:

I got a response from GPD through their Facebook page using messenger. They confirmed that even though originally the system called for 8.0 oz of oil, because the new compressor is not an HT6 style but rather a Sanden style, the amount listed on the label for the new one, 6.4 oz, is the correct amount to use.

Whew!

 

Just a FYI because I fixed my problem again just yesterday. My Blazer apparently has too much compressor oil in it, or it is the wrong type. Gets into the compressor cycling switch and causes erratic operation - sometimes A/C - sometimes not - sometimes nice cold A/C for 1 minute and then warm for rest of the drive - or warm for part of a drive and then cold for a short time - then warm again. Compressor just doesn't stay on when it is supposed to, or it never comes on.

If you unscrew the cycling switch from the accumulator, you will not lose your Freon because of Schrader valve. But if oil drips out the end of the switch you have found your problem. You might be able to clean it up, but they're only $10 so I replace them. Third time for me in several years. Then A/C works great again for at least the rest of the Summer season.

 

Final Update:

With the GPD Sanden style compressor when doing a full flush and/or parts replace so that there is no oil in the rest of the system, the correct procedure is to add the total amount of oil identified on the label on the side of the compressor to the compressor. Also note that note all oils are the same nor does a single type of oil only come with one viscosity. The OEM AC-Delco compressor pump oil is a PAG-150 viscosity oil but the GPD compressor I used calls for PAG-46, a less viscous oil.

I've created a full write-up for my installation: https://blazerforum.com/forum/2nd-ge...ent-kit-97066/