Air Conditionding stalls engine

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  #1  
Old 07-06-06, 07:29 AM
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Air Conditionding stalls engine

I have a 1998 Mercury Mystique with a 4 cyl, 2.0 L engine. When I turn the A/C on, it cools the car jut fine. The problem lies in when I come to a stop. For some reason the RPM's drop, and the engine starts to sputter and will eventually stall. This only occurs when the A/C is turned on. I was wondering if anybody might have any ideas as to what might cause this problem. Any help would be appreciated!
 
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  #2  
Old 07-06-06, 07:35 AM
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Well I would start by cleaning the idle air control motor. It more than likely has dirt on it and isn't allowing as much air to pass as it did back in the day. Plus it will only cost about $3 for yourself to do, just by a can of carb/throttle body cleaner and use a brush after you take it off.

to methods for low power engines when ac is on:

1.Your rpms are not being raised for idle when the air is turned on. ECU not receiving A/C is one signal

2.Or the vehicle is not disabling the alternator when you come to a stop.

I am not sure which one your vehicle uses and I don't have the books on your car.
 
  #3  
Old 07-06-06, 07:38 AM
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Also does it run smooth normally.
 
  #4  
Old 07-06-06, 08:43 AM
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Originally Posted by ultyguy
I have a 1998 Mercury Mystique with a 4 cyl, 2.0 L engine. When I turn the A/C on, it cools the car jut fine. The problem lies in when I come to a stop. For some reason the RPM's drop, and the engine starts to sputter and will eventually stall. This only occurs when the A/C is turned on. I was wondering if anybody might have any ideas as to what might cause this problem. Any help would be appreciated!
You might want to check with a dealer on this one as opposed to a an AC specialist. On most cars there is a circuit activated by the ECM that raises the idle speed when the AC is on. It's possible there is a problem with the circuit and it might not have a high enough priority to trip the "Check Engine" light. You could also check to see if there is excessive drag in the AC compressor when the clutch is engaged, but you did say it was
cooling okay.

Christopher
 
  #5  
Old 07-06-06, 08:46 AM
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If you know how to do electrical just get the chiltons, they are great for schematics.
 
  #6  
Old 07-06-06, 09:56 AM
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Look for the "IAC" solenoid/module. It's the idle air control and should automatically boost idle when a/c compressor kicks on.
Easy fix.
 
  #7  
Old 07-06-06, 10:47 AM
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Yes but if it were bad the engine would not idle normally, with the AC off. That is why I suggested cleaning it.
 
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