A/C almost kills the engine

[eageleye_14]

Two days ago I noticed that when I had my Explorer in Park possition that my A/C seemed not to work. The air that came out was a bit cooler then the vent but not A/C cold. Also the RPMs drops from a 1000 to 500 and up again. Well today my husband changed the oil and when he started the car and had the A/C on the RPMs get that low that it almost kills the engine while in park. In drive everything runs just fine. Does anybody have an idea what could be wrong?

 

[pmcmaster]

Under normal circumstances each time the A/C compressor clutch switches in (i.e the air conditioning compressor is working) this is detected by the Powertrain Control Module (PCM) and it sends a signal to the Idle Air Control Valve (IAC) to increase the idle speed. Either the PCM is not sending signal or more likely you have a faulty IAC. Is the Engine Management warning light on? you need to see if the PCM has logged any error codes.

 

[eageleye_14]

I rememeber a few days ago that the engine light was on. I didnt think anything of it since I didnt have any problems at that time. All I did was turning the car off and on again and the light was gone.