S10/T10 Blazer 2WD V6-262 4.3L VIN Z (1994)
A/C Signal: Description and Operation
PURPOSE
This signal indicates that the A/C control switch is turned "ON" and the pressure switch is closed. The PCM uses this signal to adjust the idle speed.
CONSTRUCTION
A/C clutch control circuit system consists of:
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Heater and A/C control assembly located at the dashboard.
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Two A/C pressure switches (LOW and HIGH).
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Compressor clutch.
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PCM
OPERATION
Turning "ON" air conditioning supplies battery voltage to the the A/C compressor clutch and terminal "E12" of the PCM connector to increase and
maintain idle speed.
The PCM does not control the A/C compressor clutch, therefore, if A/C does not function refer to HVAC section for diagnosis of the system.
If A/C compressor turns "OFF", check for an open CKT 59 to the PCM. If circuits are OK, it is a faulty PCM connector terminal "E12" or PCM.