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Retrofit - Ester oil or PAG oil

WyrTwister on Mon April 01, 2013 7:44 AM User is offlineView users profile

Year: 1991
Make: Chevy
Model: Caprice
Engine Size: 5.0L
Refrigerant Type: R12 -> R134a
Country of Origin: United States

In the future , I will need to convert the Caprice from R12 to R134a .

I have read every kind of advice on this , in the world . From " it can not be done " to all you have to do is pump it down and then gas it up with R134a " .

Unless some one changes my mind , I will probably change the schrader valves , change the front compressor shaft seal , empty all the oil I can , from the compressor , change the accumulator . Put it all back together , vacuum it down & check for leaks . If no leaks charge with 80% of the weight called for if I was using R12 .

What I hope you can tell me is , Do I go back with PAG oil or Ester oil ? I read that Ester oil is more comparable to the mineral oil that may be remaining in the system ?

God bless

Edited: Sat July 20, 2013 at 6:27 AM by WyrTwister

TRB on Mon April 01, 2013 11:33 PM User is offlineView users profile

I would you a high quality Easter like the BVA Auto Glo.


When considering your next auto A/C purchase, please consider the site that supports you:

WyrTwister on Sat July 20, 2013 6:29 AM User is offlineView users profile

Sorry I missed your reply . :-)

I am still tinkering with the Caprice A/C .

Thank your ,
God bless

iceman2555 on Sat July 20, 2013 10:07 AM User is offlineView users profile

Heck, prefer the use of a lubricant that more closely matches the OE compressor lubricant specifications. For a GM this would be PAG 150. POE's are rated at 100 centistokes which is a bit 'lite' for the GM series compressor. But over the years have seen and completed many using POE's.....the result with most GM's was a slight increase in rotational noise....never had one fail directly due to the use of POE's.
Have seen lots fail due to improper recharging.....the lack of refrigerant reduces oil flow and the compressor dies.
Please keep in mind a very important factor when retro fitting from R12 to 134a....the operational pressures are much different. The addition of 134a into a system never designed to operate with this refrigerant may increase operational, esp high side, significantly. 134a operates at app 25-35 % higher high side pressures than 12 and thusly your perceived pressures are meaningless. The system must be charged by weight and not by pressures. Consider a starting point of 85-90% of 12 specs. This is typical if the system has been flushed and thoroughly cleaned to remove ALL residual mineral lubricants.
One can do the repair correctly and complete it once...or one can perform the repair in a manner that is less than correct and often have the opportunity to repeat the repair....more than once.

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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