I just picked up a 91 Camaro RS. Amazingly clean for for 223k miles. As I was hunting down a reported overheating issue the former owner told me about (bad radiator fan switch), I noticed that the AC compressor was constantly cycling. Go inside, and the selector is in the off position. Compressor stops cycling in the vent and heat positions, and cycles when in AC and defrost positions. But it keeps cycling in the off position. So, is there an adjustment on the selector or something? This makes the 4th 3rd gen we have owned, and I've never run into this one before.

 

There really isn't an adjustment, but things wear out. Might be worn enough that the select lever won't allow the switch to move into the off position fully.

You'll have to pull it out and take a look at what it is doing.

 

constant cycling generally indicated a too low refrigerant level. When the fan switch fails owners frequently bypass it and either ground the green with white stripe wire going to the relay. Turning on the AC would normally turn on the fan as well, so look around for weird extra wiring designed to make the fan work. How does the fan function? Always on, or just when the compressor cycles on, or?