99 aurora rough idle

In the last 2 days my car is idling rough. This happens only when the engine is warm in gear at a stop. Also the heat must be on. Turn the heat control off and the idle smooths out, turn the heat on, rough idle. Seems to happen about the same time the a/c compressor kicks on. Rpm,s fluctuate between 500-700, battery voltage fluctuates with the low rpms 13.9 to 15 volts. Otherwise the car runs great down the road. ???????? any thoughts

Try cleaning the throttle body and remove the IAC and clean that up and the passages, any CEL or codes?

No CEL, I'll have to get my scanner neighbor to check for codes. In the meantime I'll clean TB and IAC, I use B-12 for that, sound OK?