K 1500 Truck 4WD V8-5.3L VIN T (2000)
Purge Mode Description
The Electronic Climate Control (ECC) module may access 3 additional purge modes when the following conditions exist:
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When the system is powered up, purge the system of stale air and/or redirect the air in order to avoid window fogging or other undesirable
conditions.
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When the ignition is turned ON and the fan increase/decrease knob is not in the OFF position, the ECC module will determine if any of the
undesirable conditions exist.
The ECC module may select from one of the following 3 purge modes in order to eliminate the undesirable condition:
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The normal purge mode
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The cold purge mode
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The A/C purge mode
Normal Purge Mode
Moisture tends to accumulate in the heater and the A/C module assembly after the engine has been turned off. When the engine is restarted and the
A/C system turns ON this moisture may be expelled from the windshield or panel outlets and cause window fogging. The normal purge mode is
bypassed if the fan is in a manual selection.
Cold Purge Mode
In the cold weather, the moist breath air from the vehicle occupants may condense on the windshield. On cold startup, the ECC module checks for
indications that this condition may occur. If this condition occurs, the ECC module performs the following actions:
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Positions the doors in order to direct air out of the windshield outlets
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Operates the blower
The ECC module then resumes normal system operation.
A/C Purge Mode
Moisture tends to accumulate in the ECC module assembly after the engine has been turned off. When the engine is restarted and the A/C system turns
ON, this moisture may be expelled from the panel outlets toward the front seat occupants.
During startup, the heater and ECC module inspects for indications that this condition may occur. If this condition occurs, the ECC module performs
the following actions:
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Positions the A/C door in order to direct air toward the floor
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Operates the blower
The ECC module then resumes normal system operation.
