Heater Blower / Fan Issue

[hotegg]

Hi,

Im fairly new to all this blazer stuff and I'm just at the start of finding my way round my truck so please bear with me.

I live in UK and recently purchased my first american vehicle, my GMC K Jimmy, and I absolutely love it.

However, there are a couple of jobs for me to attend to one of which is the heaters and fan.
When I purchased the truck the heater blowers were not working, what is the most likely course of this? is it the blower motor or could it be the switch panel in the dash?

Any help of advice on what I need to do to fix this would be greatly appreciated.

Kind regards, Sam.

 

[jt512]

I would first check to see if the blower motor is getting power, if it is not trace the power feed back to the resistor and check power coming into it. That should give you a starting point.

 

[cdoggwsu]

It couldn't hurt to check all of the fuses and underdash wiring either. That's the first thing I do on a new vehicle just to see what (if any) hacking and slicing has been done as well as looking for pinched or damaged/worn wires anywhere.

Make sure all of the wiring harnesses by the blower motor on the passenger side firewall are tightly connected and in good shape. See pic below, there will be two harness plugs if you have air conditioning. Pic is from Avery4jc's thread that may have some helpful info in it as well. View it HERE.

 

[imiceman44]

Hi,

Im fairly new to all this blazer stuff and I'm just at the start of finding my way round my truck so please bear with me.

I live in UK and recently purchased my first american vehicle, my GMC K Jimmy, and I absolutely love it.

However, there are a couple of jobs for me to attend to one of which is the heaters and fan.
When I purchased the truck the heater blowers were not working, what is the most likely course of this? is it the blower motor or could it be the switch panel in the dash?

Any help of advice on what I need to do to fix this would be greatly appreciated.

Kind regards, Sam.

There is a plug with 3 or 4 wires plugged to the air box, it has the resistors that give you different speeds for the fan, sometimes the connection there is bad, sometimes the coils inside are corroded and broken, the other thing to look for is the power wire plugged straight into the blower, it's thick and you can't miss it, sometimes it works it's way lose, I think it comes from the bottom.
Third is the control inside the cab, to know if this one works just give power straight to the blower and you'll know if it works.

 

[Fordum]

Hotegg, the resister pack is under that kinda oval shaped piece that has the plug on it you see on the right side of the picture cdoggwsu posted. Usually when it fails, you will lose one or more speeds but will still have full speed. If you decide to examine it, the two little screws are all that hold it on. BUT, DO NOT try to run the fan with it out of its hole.
The resistor pack sits in the air flow which keeps it cool. If you power the fan up without the air blowing on it, it will get very hot very quickly.

 

[tRustyK5]

One issue I had with my old Jimmy was poor ground at the motor itself. You'll notice a wire attached to one of the screws holding the fan motor to the heater box. That wire I had to clean up the terminal, scrape to bare steel and re-attach.

Cheap fix...but a little difficult to find.

Good luck!

Rene

 

[hotegg]

Thanks for all the info guys, I'll print this thread out and go see what I can do over the weekend!

Cheers, Sam.