Contour Enthusiasts Group Archives Forums General Troubleshooting Idleing

I dont know if this is common of not. I have a 1996 Contour 4 cyl. When I have the heat off as in the switch to the off position the idle is fine. Smooth and vibration free. As soon as I turn the heat on floor/def, defrost, or any other it will idle fine but every few seconds I hear a click in the engine compartment; the engin boggs down (steering wheel/dash vibrates a bit) then the engine revs up a bit then goes back down to an idle. This does this constantly every few senconds while the heat switch is on. I talked to a ford dealer and he said it sounded like the A/C compressor is turning on and off. It does this when the A/C is on also. I cannot figure it out. No CEL comes on. I dont see a problem with it other then it is annoying while the car is idling it revs up every few seconds constantly. It is probobly not good for the motor either. Could this be a faulty switch? Faulty relay? Normal on these cars? If it is the A/C why is it turning on with the heat? I thought I would start here with others whom may have the same issue.

Any help is greatly appriciated.

Travis

Check again. I think you'll find the problem only in defrost or floor/defrost.
The A/C compressor cycles when in defrost or floor/defrost in order to dehumidify the air. From your description, it sounds as if the compressor is short-cycling. Typical cause is low refrigerant.

AL

Welcome to CEG!

The A/C is cycling but the engine should not bog down.

Either the IAC is not responding well or the mixture is near it's limit.

Consider cleaning the IAC and cleaning the MAF, and looking for vacuum/intake air leaks.

Your right, when this only happens when the switch is in the floor/Def or Def position. I Replaced the MAF last year. Would it need cleaning already? What is the IAC? Where is it and how can I clean it?

Thanks. Travis

The Idle Air Control valve is attached under the intake manifold at the rear of the engine. A fresh air hose from the intake duct leads to it's base. It has an electrical connector and it's cylindrical. Sorry I don't have a pic.

Take it off and spray it out with carb cleaner. Two bolts.

The IAC is responsible for feeding air to the engine while the throttle butterfly is closed.

The MAF was just one idea for a lean condition. Air leaks into the intake duct like a bad seal or disconnected PCV fresh air tube are also possibilities.