After replacing serpentine belt, idler pully, belt tensioner and alternator, there is a slight stumble at idle when the AC clutch engages. AC works well, and this is only obvious at idle. Do I need a tuneup or a new idle air control valve?
This may also be an A/C compressor seizing problem. First make sure that the system isn't overcharged that would increase compressor load and drag the engine speed down.
Second, there was a TSB # 24-004-04 that addressed seizing compressors with a software change, new compressor and revised plumbing to prevent oil 'slugging'. Sadly, the 7/70 extended A/C warranty has now expired.
I think I'll go the tune-up route for now and assess.
The AC is working fine and doesn't sound or feel unusual, so I'm leaning against that.
The AC system hasn't been touched since Dodge replaced the condensor and recharged the system long ago.
I haven't measured the system pressures, but are there products that allow you to add more oil or improve lubrication of the compressor?
Regarding the idle air control valve, can it be "cleaned" or is it a "replace only part"?
What should be cleaned (a moving shaft, for example)?
The A/C slugging was too much oil at once and could damage the compressor. The revised plumbing got rid of a 'low spot' where refrigerant oil could pool and when the compressor engaged, it would take a gulp.
Since liquids don't compress very well, this sometimes took out a compressor.
If the system is low on oil, it could also be bad.
The IAC valve pintle and seat can be cleaned with solvent, toothbrush and rag. The throttle bore and blade also need to be cleaned of carbon where the air passes to prevent an air restriction. This is essentially a dealer's throttle body service.
The PCM will usually adjust the IAC more open to compensate for restricted air intake to maintain the correct idle speed.
Idle speed is an adaptive value. By disconnecting and reconnecting the battery, it will reset the PCM and idle speed will be relearned. Leave the vehicle to idle without giving it gas for a couple of minutes before driving it.
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