B4000 Regular Cab 4WD V6-4.0L OHV (1997)
A/C Signal: Description and Operation
A/C CUTOFF SYSTEM DESCRIPTION
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An A/C cutoff system is used to improve idle smoothness immediately after starting the engine and to improve acceleration and performance.
A/C SIGNAL
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If the A/C is on during the diagnostic trouble code check, a Diagnostic Trouble Code is output.
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If the circuit is open, wide open throttle A/C cutoff will not occur.
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If the circuit is shorted, the A/C will not operate.
WIDE OPEN THROTTLE A/C CUT-OFF (WAC) RELAY
Disengages A/C clutch during the following conditions:
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Engine cranking
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Engine overheated
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Wide open throttle
Operation
The relay is normally closed. When A/C switch is turned on, and A/C cycling switch and A/C pressure switch are closed, voltage is supplied to relay
and PCM. PCM will then verify that A/C clutch operation is desirable. PCM controls as follows:
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If desirable: Adjust idle speed and unground relay
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If not desirable: Ground relay.