Climate Control Going A Little Haywire...

[BretD04GMC]

OK, the other day my AC system started blowing hot air. I ended up just shutting the system off for the rest of my morning commute.

 

When I left work that night, I left the system off part of the way home. I turned it on about half way home and it seemed to have reset itself. Everything was working correctly.

 

This morning, I start the truck and notice the temp is set to 65°. That's not where it was set yesterday. After just a few minutes, the temp switched to 77°, the setting from last night. I turned it down to 70° and hit the recirculate button. Everything was working fine and cool air was coming out of the vents.

 

On the way to work, the recirc. shut itself off and hot air once again started blowing from the system.

 

Tonight, if the system is still outta whack, I thought I'd try a hard reboot by disconnecting the negative battery cable for a few minutes.

 

 

 

In the event that all this fails to correct the problem, what would be the next item to look at? Is there an HVAC Control Module that could be going bad?

 

Also FWIW, I did have to replace my Parking Brake Release Cable last night. Any possibility I disturbed something that could be causing this?

 

Thanks.

[gmtech4]

the control head is the module and maybe on the repair,the relay center is in the corner near the park brake pedal

 

you should have it scanned ,maybe a code is in there,no need to guess,