A single application of the air conditioning (A/C) deodorizer, GM P/N 12377951, will remove the musty odors from the air conditioning (A/C) system.

1. Turn the ignition switch to the LOCK position.
2. Set the parking brake.
3. Ensure that the cowl vent grill is clear.
4. Place an auxiliary fan in front of the vehicle.
5. Set the A/C switch to the OFF position.
6. Set the air mode to the VENT position.
7. Set the fresh/recirc to the FRESH position.
8. Set the temperature control to full HOT.
9. Start the engine.
10. Set the blower speed to HI for 10 minutes.
11. Shake the contents of the A/C deodorizer, GM P/N 12377951, well.
12. Insert the extension tube into the can nozzle.



13. Drill a 3 mm (1/8 in) hole in the blower case. Position this hole 3.2 cm (1.25 in) from the edge (1) of the case, and 3.2 cm (1.25 in) from the bottom (2) of the case.
14. Wear safety goggles and latex gloves.
15. Cover the carpet area underneath the blower case and the evaporator case with a shop rag in order to collect the deodorizer liquid that may spill out.
16. Insert the extension tube into the hole past the mark on the tube.
17. With the blower still on HI, spray the contents of the A/C deodorizer over a 5 minute period. Spray short bursts while varying the direction of the tube.
18. Turn the blower speed to the OFF position.
19. Turn the ignition switch to the LOCK position.
20. Let the vehicle sit for 5 minutes.
21. Seal the 3 mm (1/8 in) hole with RTV Silicone Rubber Sealant, GM P/N 12345739, or the equivalent.
22. Start the engine.
23. Set the blower speed to HI for 20 minutes.
24. Turn the ignition switch to the LOCK position.