HVAC problem

[strad]

Posting because it's happening more often lately. Every once in awhile, the HVAC will go full hot out the vents. Usually this is when AC is selected, but I think it has happened once when heat was already selected. When it happens, the control panel doesn't respond to any inputs. Shutting the vehicle off and turning it back on reboots whatever is causing this and it works fine again.

This is a 9/2004 Z71 suburban with automatic climate control. Where does the cause of this issue likely reside? In the control/display unit? Or somewhere else.

 

[Doubeleive]

if it is the digital control those are known to fail and do exactly what you are describing, the fix is to replace the control. I am not saying go drop your money on one but that issue can be really hard to troubleshoot, you may want to have a tech check to be sure the r134 is full first.

 

[rockola1971]

Could also be the control motor located directly left of the blower motor resistor assembly. This motor controls hot/cold. It could be stripping out BUT first as the The guy said above, start with the basics. Check your refrigerant level with gauges and make sure it is not low.