R134 Conversion - on recent LeSabre purchase.
Spent several hours Sat morning doing diagnostics on compressor control system. PCM Enable LOW on the Gn/Bk line to relay fails to operate. {Can force line low (ground) and system works well(Blows Cold) Have shorted/opened sensors on compressor & freon high/low lines to 'complete' circuits to get 'auto' mode... But still fails.
Entered clear mode and reset any that were set by my 'tampering'. Just can't get rid of code 66 (Freon Low) Removed inspected/cleaned ALL associated connectors/wires/contacts to include Control head and PCM connectors. Opened PCM to inspect for burned /failed switchers. When all went back together it worked fine for one trip to and from work cycling appropriately. But failed on next use.
Pressures in system are 'acceptable' for r134 operation and worked well for about a week. Beginning to believe one of the sensors is 'resistive' and is 'comparing' pressure.(leaking?)(threshold value?) But I don't know where that one is. I metered all snapswitches as open/closed assuming the OPENS would short at specific pressure.(inverse for CLOSED)(unvalidated transition pressure)
I really need to 'discover' the "Proper Operation Logic" that the control system & PCM requires to work auto mode. Would like truth table or diagram/description of the Control unit descrete sensor lines and their proper values for 'AUTO' operation. Anybody been here?
-Need More input!-
10-04-2005, 08:11 PM
