Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for a blower motor that does not operate regardless of the desired blower motor speed.
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This step tests for a blower motor that operates, yet does not accurately respond to the desired blower motor speed.
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The HVAC control module is inoperative when the it does not respond to any operator requests. This step verifies that there is power to the HVAC control assembly.
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The voltage will vary between 0-5 volts during normal operation. The HVAC control assembly connector must be connected during this step.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Air does not flow correctly from the air distribution outlets. | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Is the blower motor OFF? | -- | Go to Step 3 | Go to Blower Motor Always On | ||||||
Place the blower control in each speed position. Does the blower motor operate at all? | -- | Go to Step 4 | Go to Blower Motor Inoperative | |||||||
Does the blower motor operate correctly for each speed position? | -- | Go to Step 5 | Go to Blower Motor Malfunction | |||||||
Is the HVAC control module inoperative? | -- | Go to Step 16 | Go to Step 6 | |||||||
6 |
Does the mode actuator drive shaft rotate for each selected position? | -- | Go to Step 7 | Go to Step 8 | ||||||
7 | Inspect the mode door and the mode actuator for the following:
Did you find and correct the condition? | -- | Go to Step 23 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | ||||||
8 | Test the ignition 3 voltage circuit of the mode actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 9 | ||||||
9 | Test the ground circuit of the mode actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 10 | ||||||
10 | Test the 5-volt reference circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 11 | ||||||
11 | Test the mode door position signal circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 12 | ||||||
12 | Test the mode door control circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 13 | ||||||
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Important: The mode actuator connector and the HVAC controller connector must be connected to correctly perform the test.
Does the mode actuator drive shaft rotate and does the voltage change? | -- | Go to Step 14 | Go to Step 18 | |||||||
14 |
Does the voltage measure near the specified value when airflow moves toward DEF, near the specified value when airflow moves toward FLR, and near the specified value when stationary? | 0 V toward DEF 5 V toward FLR 2.5 V stationary | Go to Step 15 | Go to Step 20 | ||||||
15 | Inspect the mode door for a mechanical failure or a condition that allows excessive travel to the door. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 5 | ||||||
16 | Test the ignition 3 voltage circuit of the HVAC controller for an open, a high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 17 | ||||||
17 | Test the ground circuit of the HVAC controller for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 | ||||||
18 | Inspect for poor connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 19 | ||||||
19 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 | ||||||
20 | Inspect for poor connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 22 | ||||||
21 | Replace the mode actuator. Refer to Mode Actuator Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||
22 | Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||
23 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||
