Possible Causes
WARNING: This page is about a different car, the 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- No vacuum to function selector switch.
- Function selector switch leaks vacuum.
- Vacuum line kinked/pinched.
- Air distribution door binding/stuck.
- Vacuum control motor.
- Vacuum check valve.
- Vacuum reservoir tank.
- Vacuum actuator arm not connected to door lever.
- Heater control valve, vacuum leak.