A/C Blower fan will not turn off - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

lifl2003 · #1 06-03-2009, 04:26 PM

Hi all,

My 03 TB's a/c fan blows on high and will not turn off even when the power is turned off. I have been reading other similar thread and many people said that it sounds like the "speed control module". Could this be my problem.

I brought it to my local service station today and he said the part from GM is like $440.00 plus labor. I looked on the web and the speed control module is about $100.00. Am I being ripped off or could he be correct?

rbarrios · #2 06-03-2009, 05:38 PM

have you pulled the fuse for it?

if not- pull it- and then read up some more on here.
I think Ive seen similar post before.

RayVoy · #3 06-03-2009, 07:17 PM

Yep, your being ripped big time.

The problem I'm thinking about is in the blower speed control resistor assembly.

The problem is that the fan is blowing at high speed when the key is turned off.

If that is the problem, replace the speed control resistor. This assembly for the manual HVAC is around $20

I'm not gonna take the time to look it up (but you can search on here), if you remove one of the blower fuses, the fan will stop. I think it's fuses #35 (under the hood).
If you don't pull the fuse, or the battery terminal, you will kill the battery.

the roadie · #4 06-03-2009, 07:23 PM

They probably think it's a bad dash control module. Trailvoy knows better. It's a cheap item available in the aftermarket parts shops. No need to get it from the dealer at all.

Super 88 · #5 06-04-2009, 01:47 AM

Quote:

Originally Posted by lifl2003

Hi all,

My 03 TB's a/c fan blows on high and will not turn off even when the power is turned off.

My EXT did that ONE time. I stopped at my friends house after a 6 hour drive. Turn the key off and the fan kept running. I was tired and at first thought maybe I hadn't turned the key all the way off or something. I tried several different things, nothing worked.

I finally tried restarting the vehicle letting it run for a few seconds and then turned the key off and then the fan turned off. I was worried that my battery might be dead the next day, but everything was back to normal.

That was about 2 years ago. Hasn't done it since. Talk about weird!

RayVoy · #6 06-04-2009, 04:46 PM

Super, in the manual HVAC speed control modules, there is a relay for the #5 speed. The relay operates in #5 and the closed contacts complete the circuit to the blower.
The relay requires the key "on" to operate, but the power for the fan (fuse #35) is a non-switched supply.
Relay contacts, sometimes arc and burn, causing a pit in the contact face. Sometimes the rough surface will freeze the contact and not release it, thus leaving the blower circuit switched on when the relay has released.

bigcees · #7 06-04-2009, 05:04 PM

definitely could be the resistor,Gm has always had a problem with these being susceptible to moisture. As you will see that the new one has been changed in design it shouldn't be that much and you can replace it yourself and spend that extra money on some new mods
good luck

Super 88 · #8 06-05-2009, 12:43 AM

Quote:

Originally Posted by RayVoy

Super, in the manual HVAC speed control modules, there is a relay for the #5 speed. The relay operates in #5 and the closed contacts complete the circuit to the blower.
The relay requires the key "on" to operate, but the power for the fan (fuse #35) is a non-switched supply.
Relay contacts, sometimes arc and burn, causing a pit in the contact face. Sometimes the rough surface will freeze the contact and not release it, thus leaving the blower circuit switched on when the relay has released.

Thanks for the info. I almost never use the 5 position. 4 is usually high enough for the front, and 1 or 2 for the rear. But that's interesting.
Like I said it hasn't done it since (knock on wood)

But at least I know where to look if it does.

lifl2003 · #9 06-05-2009, 07:46 AM

Is the "blower speed control resistor" the same as the "Speed control module" Does anyone know the part #?

Thanks again!!

Mike in NY

cbwilsha · #10 06-05-2009, 11:07 AM

I'm assuming since you have the LT model that you have automatic a/c which means you need a new blower motor control module, part #89018778, which my dealer lists at $113.94. And it is no more than a 15 minute job to replace so whoever was quoting you $440 plus labor was really ready to rip you off in a major way.

Do a search above on "blower motor control module" and you will find instructions and pictures on the simple replacement procedure.

If you have manual a/c, you need the blower motor resistor. Do a search and you will find plenty of info on that option also. It is cheaper and just as easy to change.

C.B.