Heater stays on with retained power

STEVIE9520

MEMBER
2004 GMC YUKON
5.3L
V8
4WD
AUTOMATIC
211,000 MILES

This is the second replacement unit (Dorman 599-211) that I've purchased. My problem is, when I shut the truck off, the climate controls are still on with the fan blowing until I open the door (they stay powered with the retained power accessory). Not sure why. It shut off with the ignition for the first 2 weeks I had it. What do I need to be looking for? Is there power arcing from a retained power circuit? I'm a bit confused on this one. I have automatic climate controls with rear heat/AC.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

There have been reported issues with a blower motor that won't turn or some that won't turn off. There is an internal fault in the blower motor control module. Take a look through the first three pics below for the bulletin and let me know if you feel this mirrors what you experience.

The remaining pics are the diagnostics for the module.

If you haven't already, you may want to consider having the can-bus scanned to see if there are codes stored in this module. CAN stands for controller area network. Basically, all the modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them. Here is a link showing how it's done.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know your thoughts and if you have other questions.

Take care,

Joe

See pics below.

Images (Click to make bigger)