1997 Ford Taurus AC causing rough idle

Tiny
EDMILLER
  • MEMBER
  • 1997 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 45,600 MILES
My 1997 Ford Taurus has surging and rough idle issue when the AC is on. It seems to have the same issue to a lesser extent with the heat on. If the AC/heat control is off the engine runs and idles smoothly. When the AC is on the idle becomes rough when at stop lights and there is a noticeable stutter at speed even on the highway at 65. If you turn off the AC/ventilation control to off the issue is gone and the car runs fine. With the AC/ventilation control on there is a cycling/clicking sound from the engine compartment like something turning on and off about every 3-5 seconds which seems to mirror the stuttering.
I have replaced the fuel filter, changed the oil and filter, changed the spark plugs and wires, inspected the air filter and put a couple bottles of fuel injector cleaner through the motor but the rough idle and stuttering continues. Any help would be greatly appreciated.
Monday, September 6th, 2010 AT 8:36 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
The AC compressor places a heavy load on the engine, so that is why you feel it when the AC is on. The cycling / clicking you hear is the AC compressor engaging and that places the load on the engine.

Chances are the idle air control valve is bad. Has the check engine light come on?
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Tuesday, September 7th, 2010 AT 10:22 AM
Tiny
EDMILLER
  • MEMBER
  • 2 POSTS
The check engine light has not come on. I have access to a code scanner and the computer is not showing any fault codes. Would a faulty Idle air control cause the surging that I am experiencing on the highway? Thanks
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Friday, September 10th, 2010 AT 7:00 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Either the IAC or throttle position sensor could do it. However, they should set an engine code.
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Saturday, September 11th, 2010 AT 12:33 AM

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