HVAC turns itself on randomly

[Ryan05 LT]

For reference:
05 TB LT
Digital climate controls

Just wondering if anyone's had this same issue and if they have, is there a fix?
It started yesterday, I had turned off the heat and out of nowhere when I was driving, I heard air blowing. I looked down and sure enough, it was back on, only on auto this time. I usually have the climate controls on defrost & lower(legs) setting and I just hit the off button when it gets too hot. I know that when you turn either of the dual climate control knobs or press a button, auto turns on by default. But it's not supposed to turn on out of nowhere without me turning a knob or pressing a button. This happened a few times during a 30 minute drive and again a couple more times after I turned my TB off for an hour or so and made another 20 minute drive. It's going to drive me crazy if I have to keep turning it off every 10 minutes.

 

[Playsinsnow]

I too operate the defrost/floor primarily. Half the time I have something the size of a beverage, or a beverage, in drive side cupholder it touches the knob and turns on "auto". Your cupholder empty? Adjust the heat to a lower setting for the time and it you won't get swampy. Could be the digital unit. Hope not.

 

[The_Roadie]

I can't see it being anything except a real or ghost button press on the control module. I don't know of any garbled data bus message that could turn on a disabled HVAC module.

You might have contamination hidden behind some button, or something sticky caught around the edge of one. Otherwise I don't think I've ever read about this specific symptom before. Do youhave a local buddy you can swap modules with for a while?

I see four of them on Ebay right now for $50-55.

 

[Ryan05 LT]

There was a cup in the cup holder, but it hadn't moved or hit the buttons/knob. As I was driving, albeit unsafe I watched to see it the cup was the culprit, and sure enough it just turned on randomly. Unfortunately I don't have any avail, I'll have to watch it and if it keeps happening, maybe take the $50 gamble or go pull one.

 

[fadyasha]

Yes the haunted HVAC controller. I had the same in my old 03 LTZ, and never really attempted to fix it. I did notice though after disconnecting the battery for 30 Mins approximately (during the cleaning of my Throttle) the problem never happened again. Well at least until I sold it lol

 

[triz]

I used to have this happen as well. It has not happened in a long time though. I guess the ghost in my truck was hot.

 

[Ryan05 LT]

I'm not quite sure what it was. It happened 2-3 times in both instances with an approx 60 min shutdown in between, but hasn't happened in 2 days. I've made a few attempts to replicate it and now it won't do it. I'm not going to complain, but it does make me curious.

 

[cleanwaterguy]

I know this is an old thread - but...

Changed the key switch. Hasn't happened again.