The numbers below refer to the step numbers on the diagnostic table.
This step will determine if one or more blower speeds are inoperative.
This step tests for a voltage change in the auxiliary heater or A/C blower motor feed circuit.
This step tests for an open in one of the auxiliary heater or A/C blower motor speed control circuits and the auxiliary heater or A/C blower motor switch.
Step | Action | 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 review the auxiliary heater and A/C operation and perform the necessary inspections? | Go to Step 2 | |
Does the auxiliary heater or A/C blower motor operate in each speed position? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the test lamp illuminate and change intensity in each speed position? | Go to Step 7 | Go to Step 4 | |
Important: The auxiliary heater or A/C blower motor switch must be in the correct position for the auxiliary heater or A/C blower motor speed control circuit being tested. Failure to do this will result in a misdiagnosis.
Does the test lamp illuminate in each speed position? | Go to Step 8 | Go to Step 5 | |
5 | Test the appropriate auxiliary heater or A/C blower motor speed control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 6 |
6 | Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C blower motor switch. 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 12 | Go to Step 9 |
7 | Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C blower motor. 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 12 | Go to Step 10 |
8 | Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C 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 12 | Go to Step 11 |
9 | Replace the appropriate auxiliary heater or A/C blower motor switch. Refer to Heater and Air Conditioning Control Blower Switch Replacement and Heater Control Blower Switch Replacement in HVAC Systems-Manual. Did you complete the replacement? | Go to Step 12 | -- |
10 | Replace the appropriate auxiliary heater or A/C blower motor . Refer to Auxiliary Blower Motor Replacement or Auxiliary Air Conditioning Blower Motor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 12 | -- |
11 | Replace the appropriate auxiliary heater or A/C blower motor resistor assembly. Refer to Auxiliary Air Conditioning Blower Motor Resistor Replacement or Auxiliary Heater Blower Motor Resistor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 12 | -- |
12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |