Getting a code 66 (low freon) on my 1992 Regency Elite after conversion from R12 to R134a. Pressure is good, so I replaced the a/c pressure switch on the accumulator suspecting it to be the culprit. Car can site at idle for 30+ minutes, 60 degrees max fan, without an issue and compressor cycling at 10 secs on, 2 off. But as soon as you drive away within a mile it will gen a code 66 again. Been through AllData without any progress. Any comment would be appreciated.

 

This is an issue on GM cars with EATC that are retrofitted to R-134a. You will have to add a resistor across one of the system switches, I don't recall the details, but if you post the question on http://www.autoacforum.com/ , they are quite familiar with this concern.

 

Thanks! I did recheck the pressure levels and it was a bit low; however, I do still get the code (much reduced frequency) from time to time. I'll pursue the ac forum, as you recommend.