The air conditioning system can be prone to refrigerant leaks and failure of one or more pressure sensors. The AC pressure sensors should be checked for proper operation when ever the AC system is serviced.Google+
Car Problem Reports
Buick Riviera AC System Prone to Leaks/Pressure Sensor Failures
Buick Riviera Problem
Average Mileage: 81,992 mi (54,076 mi - 103,900 mi)
Visitor, 1996 Buick Riviera, 88,000 mi
ac was serviced 3 times . however after 5 days the freon had leaked out. although the tech had put a tracing die and after charging system could not find a leak with sniffer.....still a leak occured etc...HELP
service ac light on and ac won't operate. Buick service says pressure senor bad(as reported in codes). no parts available for this so they couldn't fix my problem. They reset codes added 5 ounces of coolant and it now works.
A/C leaks replaced freon with sealer.