Its a 97 Bonny. The heater control is stuck on defrost. Where do I start to look?
You have a vacuum leak on the controler
You may have lost vacuum to the actuators. Possible causes:
1. Vacuum line under the hood pulled off or cracked.
2. Vacuum reservoir cracked.
3. Vacuum line under the dash pulled off. (Maybe someone's foot kicked upward under the dash.)
4. Vacuum leak in the controller.
5. Failed vacuum actuator.