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Car won't idle

My car wouldn’t idle when the A/C or defrost was on and now it has problems (and not every time) idling and will even die when it is moving. My mechanic, though I use the term loosely, put in a new MAP sensor but that didn’t help. It had a tune up less than 10k ago… It runs fine after a short warm up. Vehicle only has 60k on it.

Make sure the battery is ok. Chrysler products won’t run without a good battery.

Sounds like you need a tech to diagnose and repair this instead of a parts slinger. You should be able to cycle the key on and off three times and the last cycle leave ignition on and it will flash trouble codes with the check engine light if any are stored. This could help us solve your problem.

The problem might be with a dirty/defective Idle Air Control valve.

This valve is mounted on the throttle body and it’s function is to allow air into the engine so the engine can idle anytime the gas pedal is released. This valve varies the amount of air entering the engine depending on the load impossed on the engine. So for example when the AC is turned on or if the vent system is set to defrost it engages the AC compressor. This puts an extra load on the engine, and if the valve fails to go to the proper position for this extra load the engine can stall.


"My mechanic, though I use the term loosely"
Perhaps a better diagnostician can help.

What year is the car? If it’s 1996 or newer, you’ll have fault codes stored in the ECU. Having those read should help.

Unfortunately, the possibilities with this limited amount of information are endless. Your engine needs a good ignition system and a good constant fuel supply to idle smoothly, especially with the added load of an AC compressor. If the engine’s spark is poor at idle (perhaps due to low coil primary voltage), if the fuel supply is poor, or if the spark itself is poor or irregular it’ll struggle to idle. It’s also possible that the EGR valve is stuck open, allowing exhaust gas to replace some of the intake air inappropriately during idle, and that’s causing poor combustion. The IAC circuit mentioned by Tester is also a good possibility.

I really think you need to start with a good shop. There are a number of things to look at here.