92 lesabre custom

[ggibson19]

My dash vents refuse to operate. A/C and heat controls work fine. The fan blows at any selected speed. I recently had the entire system blown out, therefore lots of free air movement. Now the "doors" seem stuck open at defrost/defog. Is this an electrical control panel problem, or simply mechanical? System is Manual. In VENT MAX NORM & BILEVEL positions, air blows at windshield at any temperature setting.

[yogi_123rd]

The vent system works on engine vacuum. The heater's default when there is no vacuum is to send air out the defroster. Lack of vacuum is your probable cause of your problem.

The heater/ac source vacuum line is found under the hood, to the left of and below the master cylinder. Look for a rubber vacuum line going to a connection on the firewall. This line usually falls off from dryrots.

[ggibson19]

Originally Posted by yogi_123rd

The vent system works on engine vacuum. The heater's default when there is no vacuum is to send air out the defroster. Lack of vacuum is your probable cause of your problem.

The heater/ac source vacuum line is found under the hood, to the left of and below the master cylinder. Look for a rubber vacuum line going to a connection on the firewall. This line usually falls off from dryrots.

to yogi_123rd - Thanks for the info. Found it easily, and the vacuum line had indeed fallen off. Will replace it tomorrow.