Auxiliary Blower Motor Always On (A/C Or Heater)

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

NOTE: Definition: The auxiliary blower motor is on while the auxiliary mode switch is in the OFF position.

Did you review DESCRIPTION & OPERATION and perform the necessary inspections? If so, go to next step. If not, see DESCRIPTION , OPERATION and TROUBLE SHOOTING .
Turn ignition on. Set appropriate auxiliary blower switch to OFF position. If auxiliary blower motor operates, go to next step. If auxiliary blower motor does not operate, problem is intermittent. Check for faulty connections, damaged connectors or damaged wiring. Repair or replace as necessary. After repairs are complete, go to step 11.
Turn ignition off. Disconnect auxiliary A/C or heater blower switch harness connector. Turn ignition on. If auxiliary A/C or heater blower motor operates, go to next step. If auxiliary blower motor does not operate, go to step 8.
Turn ignition off. Disconnect auxiliary A/C or heater blower motor resistor harness connector. Ensure appropriate auxiliary blower switch harness connector is connected. Turn ignition on. If auxiliary A/C blower motor operates, go to next step. If auxiliary A/C blower motor does not operate, go to step 6.
Check the auxiliary blower motor supply voltage circuit of the auxiliary blower motor for a short to voltage. Repair as necessary. See WIRING DIAGRAMS . After repairs are complete, go to step 11.
Check the appropriate LO, MED and HI auxiliary blower motor speed control circuits for a short to voltage. See WIRING DIAGRAMS . Repair wire(s) as necessary. After repairs are complete, go to step 11. If wires are okay, go to next step.
Check for poor connections or connector damage at the appropriate auxiliary A/C blower motor resistor harness connector. Repair or replace as necessary. After repairs are complete, go to step 11. If connections are okay, go to step 9.
Check for poor connections or connector damage at appropriate auxiliary A/C blower motor switch harness connector. Repair or replace as necessary. After repairs are complete, go to step 11. If connections are okay, go to step 10.
Replace appropriate auxiliary blower motor resistor. See REMOVAL & INSTALLATION . After repairs are complete, go to step 11.
Replace appropriate auxiliary blower switch. See REMOVAL & INSTALLATION . After repairs, go to next step.
Operate appropriate auxiliary blower system to verify repair. If system operates normally, repair is complete. If system is still inoperative, return to step 2.