Had one go on one of my 3 HHRs.

It was the fan switch. When I took it apart, the switch had melted internally. Probably developed resistance at the contacts and overheated.

$40 for a used control panel at the local junkyard.

Steve

 

The thing is the switch goes to ground on one side and the fan on the other for high speed. I can't figure how there is heat or arcing, without a short somewhere. An improperly installed LED could act as a short, that's why I keep going there, as could a bad diode or loose/corroded wire.

An incandescent light bulb does not make a short because it has high resistance. An LED has no inherent resistance so when it is lit it acts as a switch unless a resister is added. (a bunch of semi-conductor science left out)

 

I just noticed in the schematic there is a diode, that if bad could cause the problem.

I'm not sure where it is exactly, looks like it might be inside the BCM. Seems to say the connector is "not used", maybe the wire got connected to something somehow?

 

Wow, Don Thanks for all your hard work researching this. I have a lot to look into. As you may know, I have done a lot of work include wiring stuff on my car. I have had numerous radios in there, and have added USB ports, power plugs, interior lighting, etc. I obviously must go over it all to see what is going on. Again, thanks

 

I replaced my variable resistor -again- a few months back, and it still only worked on "high". Left it alone, in disgust, for a while, then a few weeks ago, I noticed the control wheel was feeling less-than-crisp at the detents, then it got downright... crunchy isn't a good term, but it didn't feel right at all, and the high setting was no longer working.
At almost 200k miles, I wouldn't be surprised if it was just wore out. I live in the deep south, after all.
I'm gonna replace the panel from a salvage '06 with about 40k on the clock. That should, hopefully, get me back to normal. Or at least back to having some fan control at least.

Mine is an '06, so I'm not sure how different it is, but I didn't need to mess with the radio, or even unplug the wires on the trim. I just held it out of the way enough to unscrew the 4 screws on the hvac panel, unplugged its wires (little tight, but if you do the left one first, it'll let the panel come out a little more for the other two), and was ready to plug in the "new" one.

 

Partial success. I have my fan back, only full speed though, so still something with my resistor (just got a bad one?)... or is there something else I can check?

At least I won't be driving a black car in the Southern summer without any a/c anymore. WHEW!

 

Are you aware of the butyl patch water leak on 2006 models?

High speed only points at bad resistor pack.

 

Very much so. I've re-sealed mine and reinforced it with aviation chafe tape. If I feel froggy in the future, I'll use some of my spare airplane alu-minnium to make a new patch, then seal that in, painted black to match.

I replaced the resistor pack, as I did before successfully, but this time it didn't solve the problem. I suspect that either I got a bad one (ordered long enough ago I can't really return it) or there's another issue between it and the harness.
I may go ahead and get one from a local parts shop, so I can return it there if needed (ordered the last one from ebay, so... you know...)
I'll be able to slap it in right there in the parking lot, too.

The control panel was bad, too, however, so that's fixed now.

 

The reason that only high is available when the resistor pack goes bad is that "high" connects the fan motor directly to ground.

It just hit me; why would you have to touch the radio to get to the switch panel. Just yank the waterfall off.

 

One of the 2 panels, I forget if it is the radio or the HVAC, has a tongue that overhangs the other. I thought it was the radio panel. Regardless, I snipped it off so now I can remove either panel independently.