K 1500 Truck 4WD V8-5.3L VIN T (2000)
Control Assembly: Initial Inspection and Diagnostic Overview
Function Test - HVAC System - Manual
As an aid in determining whether or not the following are operating properly, refer to the System Performance table:
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The Air Conditioning (A/C)
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Electrical
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Air
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The refrigeration systems
See: Testing and Inspection
1. The operation of the air conditioning (A/C) blower at all 4 speeds, in any position except the OFF position, and the engagement of the compressor
clutch indicate that the electrical circuits are functioning properly.
2. The operation of the A/C control selector and the distribution of air from the designated outlets indicates proper functioning.
Functional Test - HVAC System - Automatic
Complete the following steps in order to determine if the system is functioning correctly:
1. Cycle the ignition switch from the ON position to the OFF position and then back to the ON position.
Verify that the following actions occur:
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The heater A/C temperature LED lights.
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The mode LED lights.
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Both of the LEDs repeat at the same positions while the ignition is cycled.
2. Turn on the ignition.
Leave the ignition on for at least three minutes in order to allow the blower delay to time out.
IMPORTANT: The compressor does not operate at ambient temperatures below 3°C (38°F).
3. Inspect the mode sequences in order to verify that the mode sequences are operating correctly:
3.1. Set the temperature to the 16°C (60°F) setting.
Verify that the following results occur:
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Cold air flows from the instrument panel.
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The blower runs at a high speed.
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The noises level changes when the air is in recirculation.
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Hold a small piece of paper against the inside air temperature sensor holes.
If the sensor hose is aspirating correctly, the paper will remain against the sensor holes. If the sensor hose is not aspirating correctly, the
paper will fall to the floor.
3.2. Set the temperature to the 32°C (90°F) setting.
Verify that the following results occur:
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Warm air flows from the heater outlet.
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The blower runs at high speed.
3.3. Set the temperature to the 32°C (90°F) setting. Select the DEFROST setting.
Verify that the following results occur:
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Warm air flows from the defroster outlets.
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The blower runs at high speed.
IMPORTANT: Ensure that the vehicle is in a garage at room temperature.
If the vehicle is hot or cold, the system will run at a high blower speed at 24°C (75°F) and BI-LEVEL.
3.4. Set the temperature to the METRIC (75°F) setting. Select the BI-LEVEL setting. Verify that the following results occur:
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Air flows from the instrument panel outlets and the heater outlets.
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The blower speed slows down. If the blower speed remains at high speed, the blower may be faulty.
Reference to System Testing
For further information regarding the diagnosis of this component and the system it is a part of, please refer to Heating and Air Conditioning; Testing
and Inspection. See: Testing and Inspection
