I have had a heater issue for a long time in my '91 Spirit, 2.5L. I turn on the heater, starts generating heat, then it cuts off and the 'Air Bags' light comes on. I turn off the heater and the light goes off. Turn it on again, cuts off, light goes on, turn off, light goes off. I am aware this would be a ground issue but admit I know little about electrical and where to look. Can anyone help me on this with some advice? I don't want to face the winter again with no defrost.

 

You need a service manual for your car, that has accurate wiring diagrams. (factory service manual.) Then you need to start chasing circuits, to see where the problem is.

 

Yes I do have my dedicated dog-earred Haynes manual. Thank you for responding.

 

Haynes isn't the factory manual, and the wiring diagrams are pretty generic. It's rare that their diagrams actually match what is in the car. That's what the factory manual is for.

 

Most likely your problem is not with your heater core but what is called a blend door that is closing. Some are mechanically controlled with wire cables and then there are those that are push button. The push button style uses vacuum. Small hoses behind the push button assy to control the various vacuum air actuated blend doors. It's possible that an actuator arm is hitting an electrical sensor or a possible short.