I have not had the pleasure of fixing one of these setting motors,
thanks for the info Bill i guess there are more failures than i previously thought

 

I need to open up the one in my 87.. I'm getting warm air - my compressor spins up and I'm getting AC, just warm AC.

I've been through the vacuum system, checked the dash and outside air sensors, replaced the head unit relay, replaced the freeze switch, and tested all the other bits.

Luckily I ordered the transistors a couple of years ago for my spares bin.. so I have them to hand already

 

Thanks for the tip, Bill.

I went ahead and checked the two pairs of transistors. They all checked out fine.

(To do this, I disconnected the bases of all four transistors from the circuit board. Then, using the diode setting on your multimeter, take readings from the base to collector and vice versa. It should give you continuity in one direction and and open circuit in the other. Then take readings from the base to the emitter and vice versa. It should also give you continuity in one direction, open circuit in another. The transistors are 327 (PNP) and 337 (NPN) and the pins are, from top to bottom, emitter, base, collector if the transistor's 'flat side' is facing left.)