1997 850 wagon blower motor resistor

Tobers · Post by **Tobers** » 03 Apr 2015, 15:36

I've only had the car 18 months. When I got it the blower motor was whining. Put a new one in (after market), and a new resistor. It was working great. Now I've discovered speeds 1-3 don't work well ... just speed 4 works ... which tells me (I think) that I've blown the resistor. I guess I can try the trick to fix it, but I'm wondering why this happened with a new blower motor and resistor. Any suggestions or guidance? Thanks. Rick

Post by **Ozark Lee** » 03 Apr 2015, 17:18

When you say speeds 1-3 "don't work well" what do you mean? Do speeds 1-3 work at all? With a bad blower resistor 1-3 won't work at all but if yours does blow a little bit I would look at the Max Fan relay rather than the resistor.

...Lee

Tobers · Post by **Tobers** » 03 Apr 2015, 18:48

it does blow a little in speeds 1-3. Can you test the max fan relay, or is it something you just replace? thanks. Rick

Post by **Ozark Lee** » 03 Apr 2015, 20:48

You can test it with an ohmmeter but I'm not sure if the pins are labeled on the relay. With the relay out you should have a dead short (0.00 Ohms or very close to that) between pins 1 and 5. That is the path of current flow through the blower resistor to the motor. If the relay isn't labeled they are the pins associated with the green/red wire and the green wire respectively.

It is the same relay as the A/C relay that is plugged in next to it and you could swap them for testing purposes. They are a very common relay and they should be cheap at any auto parts store.

If the relay checks out what usually happens with the blower resistor is that the thermal fuse goes bad. I have heard of people crimping in a coffee pot fuse to get the resistor to work again. From the factory the fuse is welded in since it has a thermal limit that is a higher temperature than the melting point of solder. The leads are steel and they hate solder anyway. Radio Shack used to sell the thermal fuse but good luck finding a Radio Shack these days.

...Lee

Tobers · Post by **Tobers** » 04 Apr 2015, 19:18

thanks, Lee. You gave me just the info I needed. Once I got in behind the glove box I realized that speeds 1-3 didn't work at all. I switched out the relays, just to be sure, and that didn't help. So I pulled the resistor, went to Radio Shack and bought the .99 thermal fuse, and then got my neighbor (an electronics wiz) to solder it. And it works! Thanks so much! I very grateful. Rick