1994 850 Climate Control Problem

Texrevolvo99 · Post by **Texrevolvo99** » 01 Nov 2010, 19:53

1994 Volvo 850 Turbo sedan with dual automatic climate control. This is a problem with my mother's Volvo. She had started the car up with (I'm fairly certain), all the climate controls set to auto with A/C switch on, and driven less than a quarter mile to her garden plot at the apartment complex where she lives, where she parked and turned off the car while she checked her garden. About twenty minutes later, she got in an started the car to return and, she says, she immediately smelled a "pungent, perhaps burning odor" in the car. She got home and turned off the car and informed my father, who went out to check it out. Upon inspection, the "smell" had pretty much disappeared. He started the car and the fan control did not work at all in any position. After pushing and turning all the climate controls with no effect, he then happened to turn the headlight switch on, which resulted in the blower coming on at full speed. With the headlight switch on in either the first (parking light) or second detent, the fan blows at high speed and the sliding speed control switch on the dash has no effect. Also, with the fan running, the air conditioner is on and cold air is being blown with the A/C switch having no effect on this; cannot turn off the A/C. The blower turns off when the headlight switch is turned off! They took the car to the auto repair shop that last year replaced the blower motor and they said they couldn't do anything. So I have stepped in to try to help and see if there is anything I can do that will keep us from having to resort to taking it into the Volvo Dealer and what I can only think will be an expensive repair bill. I have removed the glove box to inspect the blower wiring harness, as well as the ECC unit from the dash, thinking I could see evidence of something that burned, but do not see anything. The only other thing I can mention is that all fuses are good. Does she need a new ECC unit? Is it a faulty circuit board? Thanks for any help!

Post by **jblackburn** » 01 Nov 2010, 21:39

Yes, I think you're in for a "new" ECC unit. Find one from Ebay or a junkyard that you can swap in.

The resistor might have gone out too, causing both to fry.

Post by **Red-Arrow** » 02 Nov 2010, 05:15

Electrical problems like that are a PITB. Check the relay for the compressor and look for bad earths.

Post by **Ozark Lee** » 03 Nov 2010, 21:13

Pop the ECC out and do a visual check. The easy way to do that is to slide the radio out (you really don't need to disconnect it but if you do you will need your radio code) and then just push the ECC from behind to get it to pop out of the dash.

Once it is out remove the cover and look for burned marks on the circuit board around the gang of capacitors and/or a big smoke smudge on the top of the case.

If you see either or both it is new ECC time and eBay is your friend.

...Lee