2004 Chevrolet Silverado, Blower Will Not Turn Off

This 2004 Chevrolet Silverado came in with the complaint that the blower motor will not turn off even with the key off. This is relatively common problem of the the full sized Chevrolet, GMC and Cadillac trucks with auto a/c controls. The first step is to lower the passenger side hush panel under the dash. There are three screws with 7 mm head on them. The one over the transmission hump is slightly difficult to remove and can be a SOB to install.

With the panel out of the way the blower speed controller is right in front of you as seen in the next picture.

Unplug the harness connector to get the blower motor to stop blowing. If you would like to see more details about testing please click here . To change the controller simply remove the two attaching screws with 5.5 mm heads and disconnect the remaining wiring from the blower motor.

This is a side view of the connector to the blower motor. The tab with the hook on the end has to be depressed before it can be pulled from the blower motor.

This picture shows the clip that has to be pushed in to release the three wire harness connector from the blower speed controller. It is a good idea to check the terminal spring tension in the three wire connector. To see and easy way to do this please click here. If your harness connector is damaged and needs to be replaced with the most updated part, please click here.

Install the new blower speed controller and reinstall the hush panel. This part number and design have been updated by General Motors. If you would like to see replacement information on installing the newly designed part please click here.  If you would like to order this part please click here. If you have a cabin air filter now would be a good time to change it. This truck did not have one. If it did it would have been just to the left of the controller.

One last thing that I like to check is the a/c drain tube to make sure it is present and clear. If it is restricted it can cause water to build up and the water can damage the blower speed controller. If it is missing , water will not be completely diverted away from the cab and will make its way back inside and wet the carpet.

If you would like to see a video of a similar repair please click here.

27 discussions on “2004 Chevrolet Silverado, Blower Will Not Turn Off”

  1. The small purple/white wire will not have any power on it unless it is connected to the blower speed controller, the part near the blower motor. I am assuming that the blower motor runs on high even with the key off? A simple test is to disconnect the small purple/white wire from the harness connector. Connect all harnesses and see if the blower motor still turns. If it does there is something feeding ground to the blower motor itself. Last summer I had a Trailblazer come in with that problem and I found that the antenna wire was grounding the motor housing. If it does not blow anymore then there is a short to ground on the small purple/white wire.

  2. Sparky, sorry if this is the wrong place to ask this, I appreciate all the infomation you have posted. Although its been helpful I’m still at a loss on a some what similar issue but I can not find anything additional on your site that would seem to indicate a solution to the issue I’m having. I have a 2005 2500 Silverado with A/C auto controller. The fan will not shut off and is always on high. I have replaced the fan, the module next to the fan and the controller in the dash and it still is and issue. I have followed the testing as indicated in the threads I have found. The red wire does have 12 volt the black is grounded and the purple/white is not shorted to ground. The plug ends look good no apparent damage. Here’s the rub there is no voltage to the purple/white and I have tested at the plug on the back side of the controller in the dash. Do you have additional information that may be located somewhere I was unable to find that would be useful. Thanks again for all that you have posted and done to help others out. Kevin.

  3. I have not done a repair on that situation. My personal truck does that sometimes. It is an internal problem within the control head assembly. All I have done on mine is the roll the knobs back and forth a few times to clean up the connection. On mine, I feel it does it because I rarely change the temperature setting.

    1. Sparky, thanks for all the info you put out there on the web, the controle module was the issue and the blower is back running again like its supposed to. I looked through other archives of your but havent found another answer i am looking for. My autoclimate bounces all over the place when turning the knobs. It will jump from 71 to 64 and so forth wjen trying to adjust temps. Any articles regarding this? Thanks again.

Share Your Experience: