Automotive Air Conditioning Information Forum (Archives)

bonke on Fri July 30, 2010 6:56 PM

Year: 1991
Make: Cadillac
Model: Deville
Engine Size: 4.9
Refrigerant Type: R134a
Country of Origin: United States

A while back, there were posts on converting 1991 Caddy Devilles over to R134a. There is a problem with the thermistors ( both the low and high temperature ones) needing resistors added in parallel to avoid the system shutting down the compressor and to activate the cooling fan at a lower high side pressure. I can't find these posts anymore! Can some one how has successfully converted please tell me any tips on how to do this conversion? Many Thanks...

Dave in Texas on Fri July 30, 2010 7:15 PM

I converted my '87 DeVille in '96. I've not had problem #one since. The compressor was shot when I got the vehicle, so I power-flushed everything backwards/forwards. Added the conversion adapters to the schreader valves, changed all o-rings, replaced orfice tube(White), new accumulator and compressor. Added correct amounts of oil to each, pulled a vacuum and filled'er up with 80% of the R12 capacity. When I replaced the engine in Dec '08, I replaced the accumulator and changed to a Blue orfice tube. Nothing was done to the control systems and the air out of the registers is in the very low 40s on our HOT Texas days.

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

Edited: Fri July 30, 2010 at 7:17 PM by Dave in Texas