After we finally got warmer weather my 94 has started idling erratically, revs up and down perhaps 5x a minute in coincidence with engagement of the HVAC compressor. Starting & performance is fine, fuel economy remains excellent. IAC I replaced 2 years ago (might clean to see if that has an effect), no CEL. OBD 1 readers are scarce around here, anyway last time I did have it read, was told the computer wasn't communicating. No big deal there. It's not a drivability issue yet, so insight would be appreciated.