My HVAC control is stuck on defrost, it doesn't matter if you have it on panel or floor, it only blows out the defrost. Does anybody know what can cause this?

 

Vacuum leak most likely. Defrost is the default position for your HVAC so you can at least defrots your windows.

 

Thanks for the reply, I will have to check it out. I did have the controls out last week and this is when it started. I took them back out today and when I put it back together I forgot to plug the 5 vaccum hoses back in. I plugged them back in today, but it still is stuck on defrost.

 

I would follow the lines you unplugged and see if they came disconnected somewhere. I had the same issue with my old Grand Cherokee. My cruise control was vacuum operated as well so both went out. It ended up being a single line going directly into the intake.

Vacuum leaks are a major PITA to diagnose. Your best best is to start with the ones you were messing with. From there, look for a vacuum diagram showing all lines associated with your HVAC. Your dealer should be able to provide this.

 

Alright, I feel retarded. I went outside and checked again and it works right. I guess after I plugged back in it took a while for it to read the vaccum, now after letting it sit it works.

 

Very nice. Probably just needed time to create vacuum.

 

You could still have a leak in the system, the vacuum reservoir is supposed to hold reserve vacuum for the system. It seems the vac line tends to crack forward of firewall below battery.

 

Mine has a mind of its own. I set it on panel and floor while cruising down the interstate and it will go back and forth between that and defrost at random times.