The numbers below refer to the step numbers on the diagnostic table.
Test the Low, Med 1, Med 2 and High blower motor control circuits for an open, short to voltage, short to ground or high resistance. The High speed blower motor control circuit is spliced to the Blower motor resistor circuit. This circuit should be checked also.
Check the connection by removing and securely reinstalling before replacement of the HVAC control is considered.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor operates in at least one, but not all, speed positions. | |||
1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | |
2 |
Does the blower motor operate at the desired speeds? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
Does the test lamp illuminate on all blower motor control circuits? | Go to Step 5 | Go to Step 4 | |
4 | Test the applicable blower motor control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 7 |
5 | Test each blower motor control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 6 |
6 | Inspect for poor connections at the harness connector of the blower motor resistor 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 10 | Go to Step 8 |
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 10 | Go to Step 9 | |
8 | Replace the blower motor resistor. Refer to Blower Motor Resistor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 10 | -- |
9 | Replace the HVAC control assembly. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 10 | -- |
10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |