No heater fan 94 850

waynej · Post by **waynej** » 26 May 2012, 17:17

Have the manual climate control. No power to the fan motor on any speed. Have power at the fuse box and both fuses are good. When I move the control to #4 a small blue relay clicks and a servo motor runs for a second.

Does anyone have any idea what to check next?

Samusai · Post by **Samusai** » 27 May 2012, 10:55

Does the fan speed selector switch "feel" any different when you slide it? I had an issue very similar to this just a few months ago and it came down to a problem in the contacts inside the switch. The switch felt much harder to slide and just didn't feel normal.

When I cracked open the switch module I found a lot of burn marks on the contacts.

I did my best to clean everything with a wire brush and after I reassembled everything it worked!!! ... for about a week.

I finally just ordered a replacement unit off ebay and everything worked perfectly. You might want to give cleaning the contacts a shot and see if it help.

- Sam

waynej · Post by **waynej** » 27 May 2012, 16:26

Thanks for the tip Samusai, Now how do I get the climate control out of the dash so I can get to the switch? Pulled the radio below it and can't see any type of release.

waynej · Post by **waynej** » 27 May 2012, 19:43

Got to the switch, checked ok, followed the wires and found a fried resistor. I thought only speeds 1-3 went through the resistor, I don't understand why 4 would need resistance.

Does anyone know what the resistance values are on a good resistor? I will put in a couple of wire wound resistors and have speeds 2 & 3.

waynej · Post by **waynej** » 04 Jun 2012, 21:18

Doesn't anyone have an extra resistor you could check the resistance on? It would be greatly appreciated. Also does anyone know how fan speed #4 works? Does it use the resistor?

Post by **BEJinFbk** » 04 Jun 2012, 23:39

Speed 4 uses a relay near the motor and resistor pack.
Which relay is clicking? And have you bypassed all that
stuff and applied 12 volts directly to the motor yet?
If you have bad resistors (plural), your motor may be bad.

FWIW, full downloadable wiring diagrams are right here at MVS.

waynej · Post by **waynej** » 05 Jun 2012, 09:32

Thanks BEJ,
It's the small blue relay next to the resistor pack that is clicking but no fan. I pulled the fan out and connected to a 12v battery and it ran fine and turns freely-no bad bearings. Pulled the resistor and it's both fried and cracked with no continuity on any of the 3 circuits.
I will try the relay out of my parts car and I'm still hoping someone can give me the values for the resistor.

Post by **BEJinFbk** » 05 Jun 2012, 11:00

Those are pretty high current resistors.
You may save yourself a lot of time and
effort just getting another resistor pack.

As for the relay, have you checked power
coming in and going out? And how do all
the connectors look? They've been known
to overheat and not pass current.

waynej · Post by **waynej** » 11 Jun 2012, 22:56

Used relay from my parts car, fan worked fine on #4. Turned it on and off about 6 times, then ran it for about 5 minutes. felt all wires, plugs, relay etc. nothing warm.
The next day I turned on the AC switch first and then the fan- now the fan won't work any more.Relay still clicks, opened both relays, nothing looks or smells burned, contacts look like new.
Can anyone explain what the problem is?