Blower Motor Problem

[Super Kevin]

When I crank my Tahoe, there is a 20 second plus delay before the blower motor starts on the front air. It cools great and it seems to work correctly with the motor speed once it gets going, but there is a problem with the power supply and I want to fix it. The Rear air starts immediately, so it is in the front air circuit. Was thinking that it may be the relay or the resistor, but I haven't changed it yet. I don't think the symptoms fit a diagnosis of a bad resistor. Hoping someone has experience with this issue. Any help is appreciated.

 

[aldrichg9]

Are you sure you don't have the HVAC control set to Auto?
If it is set to auto it will slowly step up the motor speed rather than come on full all at once.

Sounds simple I know but thought we could start here...

 

[Super Kevin]

Yea. I thought of that. Can't remember if I tried it or not though. I will give it a try when I get home tommorrow.

 

[Super Kevin]

Okay....The Auto Air is not the problem....And I am confused because where the resistor is supposed to be, I have this. What is it?

 

[Super Kevin]

Here's the other side of it.....Only three pins at the connector instead of 4.

 

[Super Kevin]

I think it must be the HVAC Control Module....I have also seen it called the blower motor speed control.
http://store.the-electric-connection.com/15-81773-hvac-control-module--gm-trucks--suvs-w-automatic-ac--2003-2006-p719.aspx

Here is a write up on how to replace it:
http://www.sparkys-answers.com/2009/09/2004-chevrolet-silverado-blower-will.html

 

[Super Kevin]

Replaced the Blower Speed Control Module and it now has a new problem. Most of the time it kicks on but when it doesn't, it never does. Also, I noticed that when this happens, the blower motor works in "key on", but not in when the engine is cranked. So, I did some more research and found this:

There is a new development in this repair. It seems that General Motors has added or changed a circuit in the new module that reduces what they refer to as "Thermal Events". In doing so the new module does not always play well with aged blower motors. What we wind up with is this. The blower motor will not work on an engine restart unless the a/c controls were switched off before the ignition was cycled off and back on after the engine is running again. The two immediate ways to address this issue is to learn to remember to cycle the switches in the above manner or replace the aged blower motor with a new one. I suspect there may be a software update somewhere down the road but that will require dealer level programming abilities. Since the replacement part is only available from GM or through an AC Delco distributor we are all being subjected to this problem.

It came from this site:
http://www.sparkys-answers.com/2011/07/2003-gmc-yukon-bower-erratic-not.html

Apparently, changing the module caused a new problem. Because it works fine if I turn it off before I turn the engine off.

 

[Super Kevin]

Okay. Updating this in hopes that it will help someone out in the future. The problem with the blower continued to get worse. It got to where I was messing with it every morning. Didn't matter if I turned it off, killed the engine then started it back up. It still didn't work. So, I changed the blower. That fixed the problem. So, in my opinion, the blower was worn out and that is what overloaded and burned up the the blower control module.

BTW: Changing the blower was a piece of cake. 30 minute job....max......seriously. I thought it would be more work.