A/C Problems, 99 Intrepid

[pgroves75]

I am having A/C problems on my 99 Intrepid. The A/C works intermittently. The idle speed is about 800 rpm on the car. When the air is working properly, the rpm drops to about 500 rpm and the air can operate fine like this, but not all the time. It seems like if I do anything that demands more power consumption the A/C (clutch) will start to cycle on and off, this cycling process occurs about 80% of the time. The air will sometimes return to normal operation after this procedure. If I increase and hold the rpm with the gas pedal, the air will return to normal operation. The air seems to work fine while at driving speeds (higher rpm). What would be causing this problem? I would greatly appreciate any suggestions or guidance on this matter. Thanks, pgroves75

[theFREAKnasty82]

It appears the the idle speed motor is not compensating for the increase in engine load. Is there a check engine light by any chance? If so, then it could very well be your idle speed motor. Another thing you can do is take the air intake housing going to the throttle body and check for carbon deposits. Carbon will appear as dark black soot that can gum up a throttle plate and idle speed motor arm. Go to your local auto parts store and get some carb cleaner and spray that in there, but not too much; you don't won't to flood out your engine if you spray too much.

[pgroves75]

Thanks for the reply. No chk eng lgt on. The throttle body looked fairly clean, but I will try the carb cleaner. Where is the idle speed motor located? How can I check it? I just noticed I am having intermittent cruise control problems; would this be related?

[theFREAKnasty82]

Assuming that you have the 2.7 liter, the Idle Air Control valve is located on the left side (facing the firewall from under the hood) with four wires coming from it. The colors will be gray/red; yellow/black; brown/white; violet/black. To check if the IAC valve is working properly, let the engine warm up to normal operating temperature. Disconnect the electrical connector to the IAC valve (just a bit of caution, doing this will set a check engine light, but it will reset itself once you reconnect it). See if there is a change in the idle, there shouldn't be. Next reconnect the electrical connector, put the transmission in gear, turn on the A/C, and turn your steering wheel back and forth. It should remain steady or increase slightly. If it falls on its face, the valve is defective and have it replaced.

[pgroves75]

2.7 Liter. No change in idle speed when the IAC valve is disconnected. The check engine light does not set (light) when the IAC valve is disconnected, (I did verify the check engine light does work when I turn on the ignition). I followed your steps to check the valve; the AC clutch disengages as soon as I turn the wheel but I would not consider the idle to fall on its face.

[theFREAKnasty82]

The next thing that you can try and do is to with the engine off, disconnect the IAC again, and if you have an ohmmeter, test for continuity (or an electrical signal) on the actual IAC valve. Put the leads of the meter on the two outer pins of the valve to see if there's continuity. Next confirm that there's continuity between the two inside terminals. If no continuity exists between both or one or the other, then you have a bad IAC. Let me know what happens.

[pgroves75]

Continuity test good on both inside and outside pins. Could the alternator have anything to do with this problem.

[jagdriver12]

i have the same problem did you ever figure out what it was?