Leaderboard

I would buy 2 cans of Freon if the system is just low on Freon. You might not need to add all of the second can. The compressor must be running when you are adding Freon. Otherwise you won't be getting an accurate reading on the gauge and the Freon won't go in enough to fully charge the system. Open the doors or roll the windows down so the compressor doesn't try to cycle on and off as you add Freon. If it's a really hot day I put a box fan in front of the car to help keep the condenser in front of the radiator cool. I usually put the can of Freon in a container of hot water. Doing that causes the Freon in the can to expand and go into the system faster as the Freon in the can gets low. With the compressor running, keep adding Freon until the pressure is in the correct range on the low side pressure gauge and the air is cold coming out the vents. If the system is in good working order, the temperature from the vent should get down to about 40 degrees with the doors and windows closed.

I think one form a Buick Riviera of a similar year would work. Don't think you will find a new one.

I have the standard system U1H

7th generation Rivieras did offer a Bose radio system as an option, code U1G.

I don't know much about the '91 models and zero about Rivs. Is it possible the Riv has the optional Bose radio system that have separate amps? If so that amp could be bad.