- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Air Flow Control
Air flow control is accomplished in the following manner:
Primary control is through the function selector knob , mounted on the heater function selector switch, which is part of the heater control .
The function selector knob has the following positions: OFF, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST.
The heater function selector switch combines a vacuum selector valve with an internal electrical switch.
The vacuum selector valve directs source vacuum to various vacuum control motors (18A318) . Refer to the System Airflow Schematic and Vacuum Control Charts.
An internal single-pole electrical switch is also controlled by the selector. The switch controls the electrical supply to the heater blower motor switch (18578) .
The position of the function selector knob determines the manner in which the system will operate.
Each position of the function selector knob is detented for positive engagement.
You probably have a vacuum leak , Pull heater control panel an check for vacuum . A broke vacuum hose or The vacuum selector valve is bad ! Or check for a vacuum hose in the engine compartment being off somewhere !
C Craft, it could be a couple of different things but from what you stated my best guess is it's going to be a issue with the door that diverts the air to the position that your selector knob is in on the climate control on the dash. If you can turn the selector knob and actually hear the actuator moving the door but the air doesn't change vent positions, then I would say the door is broke.
Now, you also want to check and make sure that there is vacuum going to the control. The main vacuum line coming from the engine is located around the passenger side firewall under the hood. Make sure the line is not broke or come unhooked. You can pull the control head out of the dash and actually crank the engine and check to see if it's getting vacuum that way by unplugging the vacuum line assembly from the back of the control head. If your getting vacuum to everything, then it will have to be a problem with the door itself which is in the air box behind the dash and it is not a easy fix. I would suggest having a qualified mechanic look at it if what I have told you don't check out. Hope this helps you.
The system runs on vacuum supplied by the engine intake manifold. The switch uses the vacuum to open/close the various doors in the system by actuating diaphrams. The default is usually defrost, and the system will blow on the windshield if there is no vacuum supplied or if there is a vacuum leak in the line or in the switch. See if you can trace the small vacuum hose that comes from the engine through the firewall and up to the controller/switch and check for a leak.
A vacuum hose that controls the little door that switches where the air blows from is off, its gonna be a real chore the find which one and take the dash out to get to it, but you might get lucky and be able to look underneath the dash from the passenger side and actually see it, good luck
THE AIR DOORS ARE VACUUM CONTROLED.THERE IS A SMALL VACUUM LINE THAT COMES THROUGH THE FIREWALL INTO THE DASH.FROM UNDER THE HOOD CHECK ALONG THE FIREWALL FOR THE LINE.IF THE LINE IS NOT HOOKED UP THE AIR WILL ONLY COME OUT THE DEFROST(DEFAULT MODE)
Your mode door is controlled by vacuum check the vacuum hose on the left side of the intake manifold. these some times fall off leaving your mode door with no vacuum and the default position of the mod door is defrost.