I wired in an override spdt switch in one wire on the sensor...flip it and it turns the a/c on as cold as it will go...tells the controller it's dead hot inside the car.

Instructions from Volvo when ACC goes from cold to warm on its own: disconnect this inside temperature sensor and connect wires directly. I have done it and it works fine. This sensor is there only to keep AC from blowing below 64 degrees Farenheit. If you will normally run the heater when outside temperature plunges, or use ACC to set desired temperature, you do not have much to worry about. If you want more details, you can check the Volvo manual, TSB or ALLDATA CD-ROM for $20. Anyhow, you can remove the glove compartment, disconnect the sensor, directly conect te disconnected sensor with a piece of wire, and see how it works. If you do not like it thus, you can always go and spend money on a sensor later because everything will be in place and nothing wil be damaged.

The unit is called the manual climate control unit(MCC). It's a circuit board, relay and switch device all in one. Very common problem with 700 series. Read 700FAQ's about problem with this unit and common broken solder problem on the circuit board, and it's fix by resoldering broken solder.

I had the same problem with my '92 740 but resoldering did not help my problem. New unit at the dealer $600plus. Salvage yard $150.

Good luck