Hi, I have a 2005 PT Cruiser Touring. My A/C works great whenever the car is in motion, or stopped for just a few seconds. But if I'm stopped with the A/C for more than about 10 seconds, like at a stoplight, the car will start intermittently shuddering (for no more than 0.5 seconds each time), and the A/C starts blowing warm air. Then, the light turns green, I drive off, and the A/C starts working perfectly again. Does anyone know what the possible connection is between the idle speed and the A/C being cold?

 

There may be more than one thing going on here. If the A/C kicks out, the registers usually won't blow warm air right away, because it takes some time to work the cold out of the system. Your system is now 5 years old and it wouldn't be unexpected that it might be getting a little low on refrigerant. That could account for the lack of A/C while idling and a return of cool air when running at speed.

The idle speed is supposed to be maintained by the idle air control motor, which is, in turn, controlled by the engine computer. If that system is on the fritz, if could account for some rough running at idle.

There's no easy way to check the amount of refrigerant in the A/C system. The only way to be sure of the amount is to suck out all the stuff in there and then add the proper amount back in. If you are pretty sure you're low, you could buy a kit to add refrigerant, but you'll be guessing at the quantity.

As far as the idle air control motor, again that's not an easy DIY repair and there's no guarantee that replacing it will solve your problem.

The best advice is probably to check with an A/C service professional and get an estimate on a system tune-up. Then decide whether you want to spend the money or live with the problem.

 

The idle speed is supposed to be maintained by the idle air control motor. It is controlled by the engine computer. If that system is on the fritz, if could account for some rough running at idle. You can also check you car A.C by the car mechanic.

 

Jump out and see if your cooling fan is running. If it's not, the high side A/C pressure will lugg down that little 4 cylinder.

 

I have just starting having this problem on my car - don't know why it is doing it - I have done the things suggested on this thread - but nothing seems to be the matter - maybe it it just a glitch and will go away?

 

I think if the speed of the car should not go higher every time and it should maintained properly. There is a engine computer and the car is controlled by it. You should show th A.C. of your car to any good mechanic.

 

where is the location of the crankshaft position sensor in a 2004 pacifica?? help having trouble finding it..can anyone give advise in detail?? thank you.

 

ahd929 -- it's been a while since you posted about the ac... did you find a fix and if so, what was the cause? Thanks!

 

What problem are you having?

 

I'm experiencing the exact same problem as the start of this thread:

Hoping to nail down the cause via someone with past experience, rather than paying a garage to diagnose... and still be uncertain as to the cause. ;-)