funtwodrv

Express 4500 Cutaway Chassis climate control inop. Fan not running on any speed. Removed and tested climate control related fuses in the box under the driver’s seat. All good. When I put them back in, the fan blew on high speed only. Drove it that way for 50 ft, turned the fan speed to the other positions and all was well! All speeds worked properly, AC and defrost all functioned correctly as well.
I’m beginning to suspect the fuse panel as that’s the only thing I touched. Any thoughts on where, or what else, I could look in to?

mountainmanjoe

replace blower motor speed control resistor pack

funtwodrv

Yeah, just read about it. Can it be intermittent? It’s under a bit of snow and ice this afternoon so, it will be tomorrow afternoon before I can get out to pull that resistor out.

mountainmanjoe

yup I had an intermittent one. The resistor was just kind of hanging on by a thread.

BUT, the resistors and blower motor often fail TOGETHER. The motor draws too much current, roasting the resistors. So you should do both. They don't cost much.

funtwodrv

Thanks, Although the resistors appear fine, I went ahead and ordered them and a control panel. I’ll take a look at the blower later today.
Gary

funtwodrv

Replaced the resister assembly and that appears to have addressed the issue for now. Since it was intermittent, I’m not convinced it is “fixed”.
The control panel was delayed so, I canceled the order. I’m still considering replacing the fuse panel under the seat…might order it next week.

mountainmanjoe

Check the blower motor too. The oilite bushings eventually dry out and seize up. If the motor is too stiff, it's going to roast your brand new resistors.

funtwodrv

Update: After replacing the resistors and the blower motor, problem went away until, yesterday! I wasn't able to replace the control panel as it was out of stock. So, short of that, any other suggestions come to mind? Yesterday, I tried to do some testing but failed as the blower started working as soon as I opened the hood. I did pull the resisters out along with disconnecting the cables and all appeared okay. After re-installing, the HVAC system worked properly again. There is a relay in the fuse box marked AC, could this relay be the issue? I have had the Run/Start relay go bad so perhaps, I should replace the AC one as well. I'm open to suggestions.
Gary

mountainmanjoe

what happened yesterday? Can you please be more specific?
Blower motor doesn't work? On any speed?
There is also a relay for the blower that controls only the highest speed.
Other than that it sounds like you've got a wiring fault somewhere. Nicked wire, corroded connector, bad ground etc.
You'll have to trace it out with a multimeter. Schematics are on gmupfitter.com

AC relay is probably for the compressor. But it takes a second to swap it with another one to test it out.

funtwodrv

Sorry, Just found this thread and your reply. This van is absolutely possessed! That blower was new as was the resisters. The blower would not operate on any speed. I swapped the new blower motor with the one it replaced and the blower worked on all speeds! Then I swapped it back to the new blower and it worked properly as well.
Just returned from a 1600 mile trip and the blower worked fine. Now the turn signals and the instrument panel have started working intermittently! I started another thread on that issue...

Gary