Cadillac Repair: 1991 cadillac eldorado stumbles when a/c on, cadillac eldorado, throttle plate

Question
hey Tom, i was wondering why my car idles great and very smooth when the a/c is off, then when the clutch is engaged its not so smooth.  it's a new compressor, bout 5 months old.  any ideas?

Answer
Check the throttle plate area for a blackish residue and clean the throttle plate on both sides as well as the surrounding area freeof this residue.

Next perform an IDLE LEARN procedure which is:

1. AC OFF and warm engine to normal operating temp.

2. idle in PARK with wheels straight for 5 minutes.

3. with brake applied and climate control panel in the OFF position put trans in drive and let idle for one minute. Do NOT touch the gas pedal.

4. With outside air temp above 50 degrees while still in drive with brakes applied place climate control panel in AUTO position and verify that AC compressor engages and allow engine to idle for 1 minute.

5. Put trans in PARK and shut OFF engine.