My 94 850 wagon (with the MCC) has always worked on blower fan speeds 1-3, but never worked well on fan speed 4. By pulling the max fan speed relay from behind the glovebox and putting it back in, I can get speed 4 back for a short while, but usually after a few minutes it will stop. I've recently noticed that the relay gets very hot after these few minutes, plug 87 is a bit charred. Worried that it may be a bit of a fire hazard. Please see pictures.
Is there an obvious reason why its doing this? I tried replacing the relay but it did not solve the problem. Could there be an issue with the resistor?
The charring is caused by the blower motor pulling too much current at full speed. I suspect a dirty, or failing blower motor. When the motor gets old, dirty, or otherwise starts to bind a little bit, it will take more and more current to spin it. Get a replacement motor and I'm betting your issue goes away!
