Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step will determine if one or more blower speeds are inoperative.
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This step determines if the HVAC control module and auxiliary blower motor control processor are attempting to control the auxiliary blower motor speed.
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The measured voltage on the auxiliary blower speed control circuit should increase from 0-8 volts as the auxiliary blower speed is adjusted from the minimum speed position to the maximum speed position. The voltage may increase slightly between speeds 1 and 2.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The auxiliary blower motor operates in at least one, but not all, speed positions. | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the auxiliary blower motor operate at the desired speeds? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the test lamp illuminate and increase intensity? | -- | Go to Step 8 | Go to Step 4 | |
4 | Test the ground circuit of the blower motor control processor for high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 5 |
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Important: The blower motor control processor and HVAC control module connectors must be connected to correctly perform the test.
Does the measured voltage continuously increase between the specified values? | 0-8.0 V | Go to Step 7 | Go to Step 6 | |
6 | Test the auxiliary blower motor speed control circuit for an short to voltage, open or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 |
7 | Test the auxiliary blower motor speed signal circuit for an short to voltage, open or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the auxiliary blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the auxiliary blower motor resistor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 |
10 | 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 14 | Go to Step 13 |
11 | Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
12 | Replace the auxiliary blower motor resistor. Refer to Auxiliary Blower Motor Resistor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 14 | -- |
14 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |
