QuestionMy PT idels rough at traffic lights when AC is on. When the fan comes on after what seems longer time peroid than it should it runs ok. How do I repair this?
AnswerHi Jef,
I don't have a manual for the Cruiser, but if it is programmed the way the other cars in the Chrysler line AC systems are, then it is typical for the fan to come on low speed as soon as you request AC regardless of the coolant temp. I can't be sure that it is supposed to do that in the Cruiser.
At the same time, when the compressor is activated the engine controller is supposed to send a message to the automatic idle speed motor to increase the rpm. That seems to not be happening, but only when the fan comes into play, rather than as soon as AC is requested. It could be the AIS is a bit sticky, or could be the controller is not responding properly to the AC request.
My suggestion would be to get a fault code readout and see if any numbers related to these aspects of the engine controls come out. You can get that for free at an Autozone parts store, or for around $40 at an independent shop. Let me know what numbers if any that show up, ask the reader what is the name of the code, what they suggest doing, and for how much. Then write me back and we'll compare notes using similar troubleshooting manuals for the '03-04 model years that I have.
Roland
PS The automatic idle control is a simple device that controls the opening of the side passageway for air at the throttle body throat. It might be corrective to remove the air intake hose at the throttle body and then to use some solvent and clean rag/q-tips to clean both sides of the throttle body plate as well as the throat and as well to put solvent in a modest amount in the side passageway to possibly clear out any obstruction to the free flow of air through that passageway. Use only a mild solvent as rubber is involved with the tip of the aic motor located in the passageway.
