'96 Suburban blower motor comes on after truck is parked

[Bigoilman]

Trying to help a friend out with this. Stock, low mile (<100K) K1500 with dual A/C. When he shuts it off and walks away (locked up, keys with him) it will sometimes start the HVAC fan on it's own. Doesn't seem to matter what position the fan switch was left in. Also, blows on HIGH regardless of what position the fan switch was left in. If he gets in and turns the ignition to "ON" the fan will return to the setting he left it in. What he's done so far: Replaced the blower motor resistor. Going to replace the blower motor relay behind the glove box next. Any other suggestions or are we on the right track?

Thanks.

 

[movietvet]

Check for rubbed thru insulation, crossing at a constant hot wire, especially at the back of use box. Or rodent damage.

 

[someotherguy]

The 1995-up HVAC controls are an exposed circuit board, not inside an enclosure like 1988-1994. I've seen a few get damaged when the radio was removed because the antenna lead falls down and shorts out components on the circuit board. Long shot, but not impossible.

Richard

 

[Bigoilman]

The 1995-up HVAC controls are an exposed circuit board, not inside an enclosure like 1988-1994. I've seen a few get damaged when the radio was removed because the antenna lead falls down and shorts out components on the circuit board. Long shot, but not impossible.

Richard

Good suggestion and an easy thing to check. Thanks

 

[HotWheelsBurban]

95-up HVAC control panel and switches are notorious for failing. We went through 4 on our first 99 Burb, before getting a good new one. It actually lasted till the truck got wrecked, and is now waiting for installation in my current 99 Burb. I would also look closer at the wiring, because it's crammed in the dashboard and something could be frayed or pinched, making contact where it shouldn't.
I had problems on my 97 crew cab, but it was the blower motor being worn out (it was the original one!). Replaced blower motor and no more issues.