Engine AC Compressor

Discussion in 'SN95 V6 Mustang Tech' started by Americansilver, Dec 10, 2012.

  1. Not sure how the AC Compressor works, but I have noticed when it seems to kick on, it stalls my engine a little bit. Not sure if I'm saying that right, but when I have the air off my car normally idles at about 800 rpm, when I turn the air on it idles at 1000 rpm, then when the compressor turns on it drops to 500 rpm, then jolts back up to 1000 rpm. When it drops the engine shakes.

    I'm not sure if I just need to the change the AC Compressor or if it could be another problem. Let me know if you know anything.
  2. The PCM "learns" idle trim values. As time passes, the idle will improve. The PCM also maintains two idle/trim settings. AC on and AC off.

    IF the AC is low on Freon and it is short cycling, the PCM will be unable to LEARN new AC on idle/trim settings. Hence the poor idle with the AC on.

    Either fix the reason for the short cycle (low on Freon) or jump the low pressure switch to force the AC to run long enough for the PCM to learn new AC on idle/trim settings.

    Expect the problem to return if the battery is disconnected.

    Here's some more information on how to trouble shoot Idle/IAC problems. The information is from Allfordmustangs.com

  3. Thanks alot ill look into it :nice: