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Home >> GMC >> 1998 >> Forward Control 7.4 B >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing - 5.7L >> Miscellaneous Pcm/VCM Controls >> A/C Compressor Clutch Controls >> Compressor Clutch Controls (RWD Vans)
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Compressor Clutch Controls (RWD Vans)

The A/C clutch relay is controlled by PCM. The PCM improves idle quality by delaying compressor clutch engagement until idle speed is increased, or disengages compressor clutch when idle speed is too low. Compressor clutch is cycled by PCM. The PCM smooths cycling of compressor clutch by adding fuel the instant compressor clutch is applied.