anyone know why the ac service light keeps coming on and the system only works in economy not auto 1990 fleetwood

 

Low on refrigerant?
codes?

need more info.

https://www.cadillacforum.com/m_9792/tm.htm

 

I agree. Most GM cars from the late 80's to 90's do open the circuit to the compressor when pressures are either too low or too high. The Cadillac goes a little further to tell you. Most likely low freon but could be a faulty pressure sensor, thats why the codes are needed.

 

FWD or RWD Fleetwood?

 

the same thing happened to me on my 89, It was low on r12 refrigerant.