HVAC vacuum line diagrams

Check for a vacuum leak as it is vacuum motor operated the heat door may not be opening start at engine then to control head. Pic shows vacuum lines item with arrow is for blend door.

There's is a small vacuum hose that is disconnected probably under the hood headed into the fire wall on the passengers side. Look for a small check valve to plug that hose into. It will be somewhere near or on the firewall near the rear edge of the hood, and it could be about the size of a stack of three nickels with a port on each side, or it could be the style with a built-in storage chamber.

That one is about the diameter of a quarter and about 1 1/2" long, again, with a port on each end. Your car might also use a much larger type of vacuum storage canister with the port for the hose. Vacuum-operated systems are spring-loaded to go to the defrost position when vacuum is lost. Your feet might freeze but the windshield will be clear.

Here are some vacuum diagrams (below) to help you see what needs vacuum. If you need to run a new hose to the control head to fix the problem.

Please let us know what happens.

Cheers, Randy

Both. It starts at the engine, goes to a storage canister or check valve, then goes through the firewall to the heater controls.

It should be either right at the firewall center where the heater hoses go into the car or at the passengers side outer firewall.

This is a vacuum operated system here is a diagram. Check supply line in engine compartment.

That filter affects how much air can get through, not which vents it comes out of, but it wouldn't surprise me if there was enough debris built up to where it blocked a mode door.

Happy to hear you found an inexpensive solution.

Good call, thanks for the input. Please feel free to help out whenever you are on the site :)

Cheers, Ken

Check for a vacuum leak first start at engine then to ac heat control at the back( the buttons or knobs you turn or push.) Then see if item 10 is working in drawing it will be a vacuum motor and shold pull the door so only ac will come thru.

Hello,

The small line connects to the intake manifold look for other vacuum lines and it should be there. Here is the HVAC vacuum line diagrams below. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Good to hear, please use 2CarPros anytime we are here to help.