I got an 850 GLT 1993 with the B5254S engine. After blinking the AC and REC lights its electronic climate control system stopped working. It reported the following fault codes:

1-2-4 Driver's side interior temperature sensor open circuit or shorted to 12 volts
1-2-6 Passenger's side interior temperature sensor open circuit or shorted to 12 volts
2-3-3 Floor/defrost damper motor position sensor open circuit or shorted to 12 volts
4-1-4 Driver's side interior temperature sensor inlet fan seized
4-1-7 Passenger's side interior temperature inlet fan seized
4-1-8 No control signal to blower fan power stage

After checking the wires and replacing the ECU I concluded the sensors and the damper motor themselves are defective. I've searched several Volvo parts stores through the Net but they are unable to sell them to me even as backorder.

Could someone help me in finding the parts to fix these problems and how to fix them? Is it necessary to repair the sensors to have the A/C working? Wouldn't it be enough to have just the blower signal fixed? What might impede its blower fan from receiving the control signal?

I had a problem where the blower fan and the controls for the A/C and re-circulate stops operating. If you shut the car off and turn back on it will work for a while.

The problem may be with shorted cabin temperature sensors due to dirt build up. There are about 4 temperature sensors. Two of them are located, each, near the door jams behind handles, inside roof cloth cover. (Other two are inside the vent tunnel behind the dashboard and they may not be as dirty as the other two)

I took them out and cleaned all dirt off of them. I have not have the problem since.

Ronjon
'93 850

like he said... clean the sensors... sometimes just a shot of compressed air (computer duster gas available anywhere) does it, it did for me, but I also had a bad ECC and before that happened I also replaced a damper motor myself... saved a ton on labor fees, but don't want to do it again if I don't have to
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-- current ride: '93 850 glt