Heater Stopped Working: How 1A Auto Helped Me Fix My Chevy Truck’s Blower Motor Problems

I have a 2003 Chevy Avalanche 1500 and the fan abruptly stopped working for both heat and A/C. I know just enough about cars to be 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. Turns out it’s common to have a Chevy truck with blower motor problems.

Disclaimer: That is definitely not me featured in the video above.

Diagnosing the Cause of my Chevy Truck 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 Fix My Chevy Truck Blower Motor Problems

1A Auto mechanic reviewing why you might experience problems with the blower motor in your Chevy truck

Test and Replace the Blower Motor Resistor

Here’s where I got lucky. I just happen to know a very knowledgeable 1A Auto expert, Jeremy Nutt. You might have read some of his articles or caught him on Talk & Tune.

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 any Chevy truck has blower motor problems is because of the blower motor resistor. 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.

Fix your vehicle yourself with quality auto parts at 1aauto.com

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.

Related Content

Shop Blower Motor Parts at 1A Auto

Heater Stopped Working: Chevy Truck Blower Motor Problems - 1A Auto
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Heater Stopped Working: Chevy Truck Blower Motor Problems - 1A Auto
An expert at 1A Auto helped me to diagnose why the heat in my Chevy failed, find the part, & fix it myself! Read this if you have a Chevy truck with heat or blower motor problems!
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1A Auto
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6 thoughts to “Heater Stopped Working: How 1A Auto Helped Me Fix My Chevy Truck’s Blower Motor Problems”

  1. I have a 2002 Chevrolet avalanche 1500 z71 this past fall I replaced the blower motor resistor because only 3 and 5 worked. Tonight my heat doesnt turn on at all.. I’m thinking the blower motor has crapped out but I’m not 100% sure.. could you give me some trouble shooting tips?

  2. Hi there, I just bought a used 2002 chevy avalanche 1500 Z71. Wasn’t blowing any air, so I looked into the blower motor and resister, they were both bad, so I replaced them both. Now the blower motor is working, but I’ve still got ZERO air flow coming through any vents, whether it’s hot or cold. Do you think this is one of the blend actuators?

    1. That would certainly make sense Jed. It could also be the HVAC controller in the dash that tells the blend door actuators when to move. You may have to test the circuit to see if the signal is making it to the blend door actuators from the dash controls. Also – on those Avalanches (and Silverados/Sierras), there is a HVAC water drain that comes out of the passenger side firewall (down low). If that drain gets plugged, water ends up getting into your blower motor and seizing it up. So make sure that the drain is free and clear to prevent your new motor from having a shortened life!

  3. I have a 2002 Avalanche and replace the thermostat and blower motor and still don’t have heat could you give me advice on what to try next

  4. I have a 2008 Chevy Avalanche and I had the blower motor replaced twice this month. The problem still exist, no heat the blower wont come on. My mechanic suggest that I have it diagnosed for other problems. What do you think? Any suggestions?


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