hey guys, i have a weird heater issue. The heat will come out of the front panels hot, no problems. When I switch it to defrost, only cool air comes out of the top dash/window defrost. The AC blows ice cold. Is this a blend door issue? Or maybe the heater core is clogged ? Why would the panel blow hot and not the defrost? Help please !

PS- thermostat seems to work and no overheating issues or coolant leaks!

 

any ideas?

 

Check the vacuum lines under the passenger side dash. One may have pulled loose.

 

Check.ur blend door

 

I don't think the vac lines have anything to do with heat.

 

The blend door is controlled by those vacuum lines, which if it's stuck on heat could be a problem right?

 

Could be the control module being corroded out. Depending on your model - mine was under my glove box.

That can mess with your whole switch and they do tend to get pretty corroded.

7$ part. So check it out.
How's you variable blowing? Working fine?

 

Probably corroded vac tube behind your battery on your firewall.cut off bad part and use rubber tubing from az to splice.worked for me.