2001 Chevy Blazer, 20 years old, 250,000 miles

A mini-project on the 20-year-old Blazer today. The AC fan is only blowing on high speed, and the lower speeds are inoperative. I also had this happen five years ago. The solution is an easy and cheap fix: replacing the blower fan resistor unit. Read on, for more details.

The air conditioner fan blows ice cold on "4", but that's often more than I need, and noisy. Fan speeds 1, 2 & 3 are inoperative.



Here's the blower motor resistor, mounted near to the fan on the firewall.



It removes with one electrical connector and three hex screws. Easy peasy!



It's an odd-looking critter. Those coils magically regulate the amount of electricity going to the fan, to control its speed. They look fine - it's not like the filament in a light bulb burning through. There's a circuit board in the base, and that's what burns out.



The replacement part is only $20 to $50 depending on who you buy it from. Cheap fix!



Drop it into the rectangular hole, affix with three hex screws, clip on the electrical connector. New part installed! Tested. All four fan speeds are back and working again! This is one of the easiest and quickest repairs you'll ever make.



If this part is failing repeatedly on you, then there is something else causing that. The first time I replaced this, it lasted 5 more years.

After my replacement burned out again in a short time period, I realized that something else was causing this. My fan blower motor was squealing from bad bearings - that creates some kind of electrical resistance problem, which transfers downstream to burning out the electronics in this resistor unit. So, you can keep replacing this cheap, easy resistor. But if it keeps burning out, then you've got to get to the source of the problem and replace the fan itself. I'll cover that in another post.

- John Rich

 

Good advice.

Only thing to add is that with the fan out it is a great time to clean out any debris that has gotten in and possibly blocked the evaporator.

I found lots of small leaves and tamarack needles when I cleaned out my system.

 

Good posts from both of you!