Contour Enthusiasts Group Archives Forums General Troubleshooting Poor idle when A/C is on

I have a Contour '98 SE Duratec V6 89k miles auto. Recently I found idle revs jumps up and down when A/C is on. It only happens at idle. When the shift is at P either in drive or in still, revs is stable and A/C is cold. I got this car last fall and found refrigerant was gone. I had it refilled and the garage couldn't find the leak. After that, A/C worked fine. What could be wrong? I know nothing about car. Thanks,

you are probably getting low on freon causing your compresor to cycle on and off quickly. when the compresor is on the pcm raises idle to compansate for the load and drops the idle with the compresor off. the most common ac leak is the accumulator that is located on the sub frame under the battery tray. i just replaced the accumulator on my brothers 96 'tour. most r134 hasa dye in it and should be visible with a black light. a GOOD repair shop will have one.

Ruff Idle

I've had problems with my Contour. 4-cylinder about 48K, with P0171 OBDII code. This translates into "Engine running too lean". So far I have changed the fuel filter and also the spark plugs (OEM Specs). When I have the A/C on and the car in gear it runs ruff, close to stalling but never does. I have just pulled off the injectors but have not tested anything at this point. Any recommendations? Can't find any loose or cracked vacuum lines.

I'd go as far to say that when the engine is just started and idling and the A/C is on Idle surging is charachteristic...

I will try to add some freon first. The idle surging happens when the shift lever is in P or N position, even after a long ride. If the shift is in D position, everything looks fine even when the car is in full stop. I looked through the archive and found on Zetec poor idle when A/C is on may be caused by the failure of the Air Conditioning Pressure Control Switch. Does this apply to my Duratec?