2004 weird heat issue

[71chevmal]

I have front and rear climate control. Digital control up front, rotary knobs above for rear.

In the front, I have heat, but no fan and in the rear I have fan but no heat.

I'm really scratching my head on this one. Any help would be appreciated.

[wayaboveme]

Are you hearing any clicking under the dash towards the passenger side?

[kingyugo]

I have a 05 Deville that had the same issue. it was the valve switch.

[71chevmal]

It was the module in the duct again. Normally it fails closed but this time it was open. I'm averaging one of these modules a year. Anyone got a solution?

[StumpedGMowner1]

Sounds like it has a crappy ground through the digital control and is shorting out. Instead of using the provided ground through the harness I would ground it directly to the body of the vehicle.

[71chevmal]

Thanks. I replaced it in April and it's dead again. I may have to reverse engineer my own solution.

[Cusser]

Originally Posted by 71chevmal

It was the module in the duct again. Normally it fails closed but this time it was open. I'm averaging one of these modules a year. Anyone got a solution?

I replaced that actuator in my 2005 Yukon with one from Dorman about two years ago. We had gone 2 years with it switched into the AC mode and then I disconnected the harness to keep it there.

"Loved" that I had to grind down my 5.5mm socket shorter at both ends for access, and the @$^%&*#@$^&*$# hump was still in the way !!! Other type of fasteners would've been easy to do.