blower motor switch

Post by **phils94850** » 11 Jul 2006, 07:53

i just purchased my 94 850 turbo. for some reason the previous owner hot wired the blower motor to work with the ign. key.

i guess the switch has quit working. has anyone had experience with the blower switch and how to fix ???

basically... i cant control the speed of the blower motor...

thanks everyone

utvol1984 · Post by **utvol1984** » 17 Jul 2006, 11:18

I haven't experienced this particular problem but have had the electronics apart on my 93 850 recently. As you know, fan speed is ordinarily controlled either manually or electronically by your in-dash controller unit. Evidently the previous owner circumvented the factory controls due to loss of OEM fan control. In my limited experience, loss of ability to control fan speed could be caused by a bad fan motor resistor, bad fan motor or even a bad in-dash controller unit. Assuming your fan runs full-blast (and again based on my limited experience), you can assume the fan motor is okay. I'd say the most likely culprit that caused the previous owner to jury-rig the controls was a bad fan motor resistor.

I suggest removing the passenger side trim panel under the glove box and the metal knee bolster (three bolts - two on the right and one on the left) and carefully inspecting all the wiring from the fan and to the fan motor resistor. In order to get at the resistor you'll have to cut some plastic ties that restrain wiring bundles. There's a plastic tab just to the left of the fan motor that screws into the firewall that essentially covers the fan motor resistor. If the previous owner bypassed the resistor you should be able to tell. As I understand it, the resistor allows us to run our fans at less that full- speed as desired by dissipating heat that results from unnecessary voltage being sent to the fan when it's running at less that full speed. If necessary I'd even pull the control unit from the dash to see if any of the wires from the three plugs have been cut or spliced.

I suppose it's possible that the previous owner didn't alter anything and that there is just something wrong with the fan speed switch in your dash control unit. Based on my recent struggles with control units and fan blowers and resistors though, I'd be surprised if the problem is with your dash control unit.

Finally, if you find no wires cut or spliced and want to take a stab at a fix and are willing to gamble about $95 I would replace the fan motor resistor. Remember though I'm basing that on my experience struggling with mine for several months before figuring out the problem.

I am by no means an expert and I'm just sharing what I found working on my car but I hope it might help a little.

Post by **phils94850** » 17 Jul 2006, 16:31

utvol... thank you for the input. i believe your right about the resistor. i had a merkur xr4ti and the blower would only work on one speed and it had a bad resistor also. on those cars your able to take the resistor out and replace it costs about 2 bucks at radio shack. i need to get this one out and look at it. thanks again..

utvol1984 · Post by **utvol1984** » 18 Jul 2006, 07:07

You are more than welcome - although I'm no expert - if I was I would have figured the problem out much more quickly! If you decide to replace the resistor I highly recommend FCP Groton - I have purchased many parts from them and received outstanding service each and every time - plus their prices are the best anywhere as far as I can tell.

steve · Post by **steve** » 18 Jul 2006, 22:40

I just ordered a resistor from eeuroparts.com and their price is about 10-15 cheaper than Groton, with free shipping.

My 2 cents.....

S

Post by **phils94850** » 19 Jul 2006, 09:07

thanks for the info steve.. ill check it out.