GMC /Chevy Truck Fan Speeds

guido

Well-known Member
Hello,

The fan speeds are all gone except high. They seam to fail on many of this type of vehicle. I little research I did it sounds like the big truck have a recall, not the smaller ones like the Chevy Colorado or the GMC Canyon. BUT ..................They all have the same problem! Any of you have the same problem? They say it is a contact issue with the motor harness,
and new ones are available,

Guido.
 
I've had that problem on a couple of Fords. The problems were the switches. The switches cost something like $12 for one and $14 for the other.
 
My 2004 fullsize Chevrolet got to run on high only,was a relay? /switch? on the side if the heater box in the cab. Easy fix, not much $$ for part.
 
Not sure what year you're dealing with, but back in 2007 at the vocational school I got to change a blower resistor "module" on a 4 or 5 year old GM passenger car. It's about the size of a credit card, rather than looking like the "old-school" resistors we all know.

High blower speed bypasses the resistor; all the other speeds pass through the resistor circuits. Based upon my experience, I'd suggest testing the resistor before you start parts swapping.
 
The problem is the blower resistor, BUT, take a good look at the harness and plug for signs of heating and or melting, this is COMMON .The price of the wiring repair kit at the dealer is more than twice that of the part itself, go figure. Expect repeat failure if that plug and wires are not up to snuff.
 
Probably the resister pack, but the blower motor could be drawing too many amps and that would cause the resister block to fail.
 
Well darn it - GM still hasn't fixed that???? The heater fan in my grain truck only runs on high. It is a 1958. LOL

I've just gotten used to boiling and stripping off clothes if I use it to haul bales in the winter. I haven't thought twice about fixing it. I guess you are just happy it works when it is that old. It would make me nuts if the pickup did that.
 
Hello,

Here is what is happening 2006 GMC sierra.
Fan will not work on 1 or 2 speed, ok for the all the higher speeds.
2005 Canyon fan only works on high speed, occasionally will work on all speeds, but not for long!

Guido.
 
I know from experience with a few different GM products I've owned or used at work they seem to use poor quality switches. My '98 K1500 is just now starting to become somewhat intermittent at different fan speeds. I just have to wiggle the control. Not sure about the 2006 but in my '98 the whole heater control assembly must be changed as a unit. I have a spare one that was fried by my stupidity when installing a stereo years ago but all the controls are still like new. I will replace them when it becomes an issue. The other thing I find with a lot of GM (and other) manufacturers is that soldered connections fail due to heat/cold and vibration found in all vehicles. The are just not a suitable connecion to use for larger, high current applications in a vehicle. Last year I had to take apart the 4x4 dash switch and re-solder the switch to the circuit board and it's as good as new now. Problem is when you take it to a shop they go ahead and swap out the whole switch assembly, they don't have the time/knowledge to take it apart and actually fix the problem.......parts changers!! :roll:
I know I've saved quite a few bucks over the years for myself and others, soldering up electronic dashboards, switches, heater controls,.........the sending unit in my fuel tank. The list goes on.
 
Hello Inno,

Thanks for the info. I too get to solder, many times that is the problem.

Guido.
 
Hello,

Here is the wiring diagram for the Canyon.
Now the fun begins!

Guido.
a133366.jpg
 
Well even though it's a newer vehicle and the heater controls employ "logic" (a computer), you still have an analog switch and a resistor pack. Or is that an analog switch? No, looks like another darn control module! I'd go for the resistor pack first. Did the speeds go out one at a time or all at the same time? From what you describe it would seem that the resistor second from the right is open or intermittently open. Not sure if it's serviceable or if you have to replace as a unit. I love troubleshooting! Most people look at me funny when I say that but I have lots of business from the local classic car club when they run into something they can't handle.
 
I changed the resistor on my '80 Celica once because of the same problem. They mounted it in the incoming air stream to provide cooling for it. Might want to look around the air box if you can.
 
Hello Super-H-Mike,

It sounds to me that it is a lose connections also. I may not get to it till next week though. Just too many irons in the fire now.....

Guido.
 

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