RepairPal is your advocate for car care advice and guidance

Q: Air only through defrost vents on 2002 Mercury Cougar

Hello. I'm in Afghanistan and can't look into this at this time so I'm looking for a little help. My wife's 2002 Cougar will only blow heat or AC through the defrost vents. Any idea where to start looking? Also she stated the left (I think) blinker works sometimes, sometimes it doesn't and I know the driver door window doesn't always want to roll up but I think that may be the switch or wiring in the door. Doesn't seemed jammed and trying the switch a couple times will usually make it work. Right now my main thing is to get her heat and AC working. Anyhelp you can give is much appreciated.
Get a Repair Estimate
Guaranteed by certified locations nationwide. Learn more
RepairPal estimates are guaranteed at over 1,700 quality certified locations nationwide. Learn more
The airflow in the A/C and Heater system is controlled with vacuum. The vacuum is supplied by the engine and the vacuum is distributed to Air Dampers that divert the airflow to the floor/vent/defrost vents. The control head determines which damper opens and closes.
So, what happens is that if there is a vacuum leak in the system, the airflow is automatically directed toward the defrost vent. It does this for safety, so you will always have the ability to clear the windshield.
You will want to check for vacuum leaks in the airflow control system, it could be a hose, bad damper or the controller is defective.
The window sounds like the switch or the motor, fairly common for either to fail.
Good Luck with the car, and Thank You for your service in Afghanistan! Let us know if you need any other assistance!
Didn't find what you were looking for?