Enthusiast
03 Heater issues
Hi
i have an 03 GMC that has the dual zone control for the heater.
The blower motor stays running on high no matter what you do including shutting off the truck.
The fuse has to be pulled to shut it off.
Any ideas on where to look?
I have changed the control panel with a used one with no change
Thanks
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews
Administrator
The 2003-2007 (Classic) dual zone HVAC has a unique resistor/control module. It is different than previous years and/or single zone HVAC resistor modules. High blower speed is direct 12V from the resistor/control module, which is always powered (as you've found), but electronically controlled by the HVAC head (control panel). It's located in the blower duct, accessed from underneath (up, from the passenger floorboard), below the glove box, and covered by the insulation cover. The large cover (if it's still there) between the tranny hump and blower motor, with 3 screws, one hidden above the hump in a vertical hole (7mm hex head, IIRC, same size as the others). It's been a while since I replaced one, but I don't recall it being too difficult. It's also a good time to drop the blower motor and clean out any leaves/debris that's collected in it and the duct/coil area over the years.
Enthusiast
Thank You
I appreciate the direction to go.
Now to get it in a warm place to deal with it.
Sounds a bit easier than getting to the fuel tank on my Bobcat
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews
Administrator
Most definitely easier. Your Bobcat is a fuel tank, with a bunch of accessories attached to make it more useful.
Enthusiast
Bobcat made it inside with a temporary tank...
The fun will be getting to the issue
Is this the module i need to find when i dig into the heater?
Thanksheater modual.jpg
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews
Administrator
It looks about right, but like I said, it's been a while. Look up the manual A/C module and compare size, connector pins, and price. It should be smaller w/o the finned heat sink, and near 1/2 the price. It's best to match the part by VIN, through any mainstream supplier. If it were me, I wouldn't try matching parts before laying eyes on the original, simply because it's easy to do. You can remove the cover and leave it off until finishing the job (it has no operational function). Napa shows the part similar to yours with auto A/C, at $85, Autozone is similar, and less $$. If it comes with a wire harness or recommends one, it's probably a universal fit, and wire splicing may be required. I'm not familiar with the later modules that require splicing, or have multiple mounting holes. I've only replaced OEM parts, probably before universal parts were available to also fit later models.
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