90 PA heater stuck on hot and in foot mode

[GMFreak38]

For awhile I haven't been able to select anything other than foot vents in my Park Ave with the electronic climate control. When I select body level or defrost I can hear a flap move but very little air is deflected from the floor vents to either the body level or defrost vents. Someone mentioned to me that there is some control equipment behind the glove box, so I looked there. There's a metal rod that is completely disconnected from whatever it's supposed to be connected to. I touched it and it freely moved, and since then no matter what I set the temperature for it blows the hottest air temp possible and the auto setting constantly keeps it on high blower. Before I touched the metal rod, it at least controlled the fan speed and temperature automatically. Can anybody give me any pointers on how to go about fixing this? Any help would be much appreciated.

[HotZ28]

First, hook the rod back up to the actuator, or blend door. You could also have a vacuum problem. Start with the engine vacuum line going to the canister mounted on the firewall and be sure the canister is not leaking.

[GMFreak38]

Originally Posted by HotZ28

First, hook the rod back up to the actuator, or blend door. You could also have a vacuum problem. Start with the engine vacuum line going to the canister mounted on the firewall and be sure the canister is not leaking.

Where is the vacuum canister? I think a clip broke where the rod hooks to the controller. I'm gonna have to try and hook it back up but there isn't much clearance. What exactly is the part called that controls all this? Does it also control vent selection? Thanks for your help.

[HotZ28]

Originally Posted by GMFreak38

Where is the vacuum canister? I think a clip broke where the rod hooks to the controller. I'm gonna have to try and hook it back up but there isn't much clearance. What exactly is the part called that controls all this? Does it also control vent selection? Thanks for your help.

The vacuum canister should be on the firewall next to the windshield wiper motor. Follow the vacuum line from the intake manifold to the firewall and you should see a round plastic canister. The programmer controls the vacuum & electrical supply to the actuators. The actuator on top of the heater core has an electrical driven motor; the others are vacuum. Before you hook the rod back to the actuator or blend door, be sure you can move the blend door the full stroke by hand to check free movement. If the door is binding that could be the reason the rod clip broke. BTW, before you hook the actuator rod back up, set the display to full heat, move the blend door to full heat and then you can connect the rod clip.