air flow problem

[C4POWER]

85 manual heater/AC controls, in any mode, heat-vent-defrost- equal amonts of air flow thru all vents , floor, defrost and vents, I pulled out control unit and all vac lines appear to be in place and none are cracked or brittle, is there a check valve anywhere that I am missing like on the newer C4's?

 

[Schrade]

Welcome onto the boards there!

Can you tell changes in fan speed with each speed setting? Is there blockage on the fan intake? 'Appearances' of the vacuum lines at the control doesn't mean too much just yet...

 

[C4POWER]

Yes you can detect each change in speed no blockage that i can see , and the air comes out equally of all the vents floor and vent and defrost, im stumped- all i can guess is that there might be a check valve that i cant locate

 

[93Rubie]

You are probably going to have to use a vacuum pump to see which "circuits" work and which ones don't. Also check to see if they can hold vacuum. In case of failure default position for vents is DEFROST, so you'll always have clear windows, safety thing. Get a FSM if you dont have one. They should have vacumn line diagrams in them.