Stuck on Mix

I have a 2002 GMC Safari van. The vent no longer works, it is always stuck on floor/Defrost mix. Does anyone know, is this in the control switch itself or is it something else. Appreciate your help!

What you describe may be the default mode when the HVAC system loses it’s control vaccum for the various blend doors in the HVAC system. Before suspecting the control switch, check under the hood for any vacuum hoses that are disconnected or leaking that supplies vacuum to the HVAC system. 90% of the time that’s where the fault lays.


This happened to me on my Dakota last winter. There was a control arm that became detached from the vent system. To fix it the dash had to be torn apart and the arm put back on. Nothing broken, just lots of disaseble and reasemble

Thanks, I’ll check that. I didn’t want to buy the control switch unit until I was sure, they’re about $160.