Need help figuring out what part is bad in my system. My blower motor works great when the truck is cold and first started. About 2-5 min after the truck is running, when a small amount of heat builds up, the blower motor slows down to a very slow speed, slower than any setting. It only does this in the winter, in the summer it works great. Is it the Blower Motor or the Resistor Pack? Not looking forward to cutting the box apart, so the less work I can do the better! Please Help!

Thanks
Mark

Oh Yeah, sometimes it wont even run at all upon start up, but if i get out and punch the ac/heater box it will work for a little while. Started to act up last winter, but it made it thru, the summer it worked awesome, but now below 32 again it doesnt want to work much.

 

Sounds like bad brushes inside the motor. If it acts equally bad on all fan speeds, then the motor is on its way out.

 

I just had a similar problem with my '96 Blazer. I just replaced the blower motor, and now it works great! Now, my problem is sometimes I have heat, sometimes I don't.... LOL!! I'm in Wisconsin too, so this is a problem!

 

its the blower motor im having the exact same problem as you ill hit a bump itll go on for a few minutes than not at all worked great during the summer now its crapped out before going through the trouble of replacing the blower motor check the fuses and relay and make sure its not just a bad connection.

 

Again, the answer has been given.