My 85 has a wierd problem. I have no idea how this is happening but all of my heater is blowing into the cab in one manner only...through the vents on the dash. If I push defrost, no go...even though I can hear the button click and see that defrost is selected no air is going to the windshield. If I push heat, nothing goes to the floor. It is all coming out as if the bilevel option were selected. What could be the problem??

 

I had torn my dash apart on my 85 some time back and didn't quite get all the connections right as the empty light hasn't worked, but that wasn't worth me pulling the dash apart. Now this was in the summer...have I used the heater since then??....I don't think so. But somehow I don't think that this is an electrical issue, is it?

You lost a vacume line. The doors are driven by vaccume and what you are seeing is the default position. This is an easy fix.

 

nippper

quick check would be for the vacuum line going from the intake manifold to a vacuum canister, and from there it will go across the back of the engine bay, then through the firewall to the heater controls.

 

If that tests fine, sounds like you get to pull the dash apart to re-arrange hoses behind the heater controls

If you had the dash apart, you're probably missing a vacuum line connection somewhere. You'll have to get the dash covers off again to get to the vacuum connections.

 

If you have a vacuum pump and gauge, it will make troubleshooting much easier.

 

My heater controls weren't working this summer, and I had to troubleshoot the system. It turned out to be the little gold-colored surge tank that was hooked up backwards. The one-way valve in the tank was blocking the engine vacuum from getting to the controls. 2 hoses flipped around, and everything worked perfectly.

You lost a vacume line. The doors are driven by vaccume and what you are seeing is the default position. This is an easy fix.

 

nippper

 

Thank you all so much! It was an easy fix