1994 850 T 2.3L Electronic Climate Control ECC


Symptoms were flashing Rec and AC lights for about 2 minutes not just the 20 second kind. All dampers stuck open and most A3 code failures. Fan worked on sliding scale but directional selector has no effect.


I bought a used ECC module on eBay for $59USD. Based on all my internet readings all symptoms pointed to a bad ECC module including the Volvo dealership diagnostics which cost $150USD. I disconnected the battery and replaced the ECC module but fuse 31 blew and SRS module circuit board melted along pins A 5, 6, 8, 9, 10 just like my original ECC module. I twice re-soldered the original board with the same results, that's why I purchased the eBay module. Well it turned out I had multiple fused wires under/behind the passengers side SRS black metal knee plate. I traced and replaced about 20-25 bad wires and 2 connectors. I completely rewired the AC switch connector. Fabricated connectors from $18USD Radio Shack wires and connectors. Securred everything with zip ties and electrical tape. Apparently Volvo repairmen left the wires dangling when they did numerous repairs over the years. (I'm the original owner and stopped using Volvo for any repairs about 3 years ago.)

I hope this helps someone else!

 

That must have been a nightmare. Greatly appreciate your sharing valuable info with us.


JPN

 

WOW, that was some banged up job. Happy to see that everything is fixed.

 

I have similar issues on my 93 850 n/t. Fan does not always work and selector switch stuck on i think auto. Am I looking at a new ECC module?

 

no. your 93 does not an an ecc. it has the manual control (mcc). it sounds as if you have a bad blower motor.

 

Looking online I can't tell the diff between ECC and MCC. What's the diff? If the blower motor was going out, would it only come on half the time or would it just blow slower? It does both btw?
Edit- nevermind I got it, noobie moment

 

Check to see if you have a cabin filter under the hood under the right passenger side windshield wiper. Recommend you check all your wiring near and around the fan, a/c switch, MCC, ect., all behind the glove box. Could be loose wire or short.