I know just enough about cars to be dangerous. Well, that isn’t true—it’s my blind confidence that makes me dangerous. So when the heat went out on my Chevy Avalanche that I purchased a week before, I knew I wanted to fix it myself.
I have a 2003 Chevy Avalanche 1500 and the fan abruptly stopped working for both heat and A/C. It was a chilly ride home from Home Depot, that’s for sure!
Diagnosing the Cause of my Chevy Heat Failure
Trying to diagnose why the heater stopped blowing air, I turned to 1A Auto. I read an article on the 1A Blog about A/C failure. It was a thorough article on generic A/C issues but also covered when the fan stops working entirely, so I thought I could get some insight.
After removing the blower motor, I confirmed about 12v coming out of a 2 pin connector. I also hooked the motor directly to the battery and the fan started spinning, so I knew the problem wasn’t the blower motor. I didn’t have a way to test AMPs going through the wire when I changed the resistance. At this point, I assumed the problem was with the control panel but wasn’t sure how to troubleshoot it.
How 1A Auto Helped
Don’t have a Jeremy in your life to help you diagnose a car related issue? Tell us in the comments. We’ll try to help. We might even post an article about it!
As soon as I mentioned the heater problem, Jeremy already knew a clear and definitive course of action. “By far, the most common reason that Avalanches (and Chevy trucks in general) have that problem is the blower motor resistor.” That is a direct quote from Mr. Nutt. “They fail in a variety of ways,” he went on. “Sometimes the blower runs 24/7, whether you are in the car or not. Other times the blower will only work on high, and sometimes the blower motor doesn’t work at all.”
To summarize the rest of our conversation, he suggested replacing the blower motor resistor. The standard way to troubleshoot blower motor resistor failure would be to test the voltage going through it with a wiring diagram. Since blower motor resistors are inexpensive, easy to replace, and fail commonly in Chevy trucks, it made sense to just skip that step. Jeremy was so confident, he even offered to buy me a coffee if it wasn’t the resistor.
Finding the Right Blower Motor Resistor
Then comes the good news and the bad news.
The good news is that 1A Auto has 2003 Chevy Avalanche blower motor resistors in stock, for a good price. The bad news is that there are a few options to choosing the right one.
- Manual or automatic temperature control? It’s a manual if you have a knob with low, medium, and high. It’s automatic if you can set the temperature to a specific temperature, example 77 degrees. I have a manual temperature control, if you’re curious.
- How many screw holes does it have? To choose the right one, you need to match the picture with the original part. You can get to it under the dashboard by removing the screws that hold the kick plate up.
How the Blower Motor Resistor Replacement Went
I found the part I needed and ordered it. Shipping was free! That’s always my favorite. It showed up at my door in a few days, right in time for the weekend. I watched a video from the library and was able to replace the blower motor resistor in about 15 minutes. I’m sure the suspense is killing you. But this, like all stories, has a happy ending. It worked!
I am camera shy so I didn’t record my installation of the new resistor. However, here is the how-to video I followed.
Replacement Plug May Have Been Needed
Before I wrap up, I want to leave you with something else to look out for. This wasn’t an issue for me, but Jeremy advised that I check out the plug. Sometimes when the blower motor resistor fails, the wires that go to them melt. If that happens, it’s another easy fix. You can also get the replacement plug at 1AAuto.com. Just make sure to look at the plug before you order the resistor so you can order them together, if needed.