Our express 3500 is not blowing any heat in the back only. This is a new vehicle to us and we have checked everything per the user manual and its just blowing cold air. Fan control is working fine. Front heat is nice and hot. Ideas? It’s a 2017 LT Express with front and back climate control. The only thing that is not the same in our van VS the manual is there is only one rear climate control in the front, no AUX switches. No second controller in the rear rows. I can’t say for sure if the AC is working in the back, it def switches in the front, its too cold here to test and be sure. I’m hoping it’s just a blown fuse.

 

you said the fan works so it's not a fuse.

the rear unit has a heater core, just like the front, with coolant lines running the length of the vehicle. The previous owner could have blocked those line. It's common. Feel if they're hot. Then follow them to the blockage.

 

Thanks, but what method would someone use to block those lines?

 

the vacuum valve is plastic and can break in closed position like mine was.I had a small ball valve laying around sooooo mine is manual now. Off in spring,on in winter. No big deal for me to raise hood and turn