Heater blower stays running

[TBLT03]

On a 05 TB with auto air,after you turn off the key the heater blower fan stays running. Had to disconnect battery to stop.All the controls switch the heater when truck is running but when I turn off truck heater goes into defrost and fan continues.
Is it the switch or the resistor or something else ?

Thanks

[the roadie]

It's your blower speed control module - that fits in the plenum behind the glove box just like a resistor pack for the manual control vehicles.

http://forums.trailvoy.com/showthrea...hlight=1580567

[TBLT03]

Yes, it was the module, Delco part # 15-80567 or GM # 890118778.
Paid $151.00 Can. at GM dealer.
Thru Amazon AC direct the price is $67.65 + shipping.

Should have shopped around

thanks.

[dragonsprayer]

Hi i just joined today - i read many posts on this forum so i joined - sorry if hijacked your thread but i am sure you will not mind.

I have problems with the blower both summer - would not come on when it was real hot the air.

Then the would not blow - read it was a resister and resistor modular - in this post i see it may be a blower controller modular not the resistor.

i have a LT with auto air/heat controls on the steering wheel.

A day ago the blower went from only the lowers power, rear works, to fully on. Last night it stayed on all night, my wife said it would go off - it did not and killed the battery.

So we went from no blower, to full blower to blower on when the car is off. How can the blower be on with the car off? I do not understand when the key is off their is no power too the blower - right? i guess wrong?

is this the same part as listed in this thread?

thx RWR3! this is great forum!

ps: i appreicate the help we too like many got hit hard from the economic depression

[Atlwrk]

Follow Roadie's link in post #2 or just replace the module with the part in post #3.

[dragonsprayer]

Originally Posted by Atlwrk

Follow Roadie's link in post #2.

i was pretty sure - thx - i wanted confirmation.


if i got this right, the resistor problem is only manual while the control module is the auto resistor which controls the wattage to change the speed through either voltage mod or amps

is my fan motor may be bad too - could that cause the issue of the module?

108,000 miles - i read other posts older fans put a strain the resistor on the manual so could i need to change both? i guess if it goes again i know?

[the roadie]

Originally Posted by dragonsprayer

How can the blower be on with the car off? I do not understand when the key is off their is no power too the blower - right? i guess wrong?

GM designed the system to have constant 12V straight from the battery available to the blower speed control. They trusted that when the ignition was off that the speed control would not fail in the ON position.

They were wrong. Bad engineering.

If the blower power went through the ignition switch for safety, the ignition switch would be even larger and more failure-prone than it already is. The designers had a good idea, they just failed to design all the components as well as they could have if they spent a dime more.

[dragonsprayer]

thx - i understand - i really appreciate the reply

i see the logic - perhaps i should put and on/off switch on it?

[tricguy007]

They were wrong. Bad engineering

[johnecox3]

Roadie,

Man thanks for posting this. Its been driving me mad! My question is that I looked behind the glove box and cannot see the speed control module. Is it in a different location for a 2003 envoy?

In addition is it the same part that is needed? I have the same issue. The heat and ac will go from a slow blow to a full blow and then when the car is off it will still blow until the car is dead.

Thanks.