when the A/C Clutch kicks on, .. you experience a 200 rpm dip when the clutch comes on...even when heater is on
rpm drop on 1990 Chevrolet Camaro
The idle air control motor is supposed to sense the air conditioning compressor having come on and automatically raise the engine idle speed. With the engine running turn the steering from side to side full lock with the head lights and other electrical loads, does the engine speed also drop when these loads are put on the engine? If so the idle control is not working properly.
1 more answer
autotechpat is right. first step is try a throttle cleaning. the idle control may be at its limit if normal air flow is too low.