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 module.
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The voltage will vary between 0-5 volts during normal operation. The HVAC control module 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 | |||||||
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 | ||||||
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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . 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 . 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 | ||||||
