A single application of the air conditioning (A/C) deodorizer, GM P/N 12377951, will remove 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 the cowl vent grille 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 lever to the FRESH position.
8. Set the temperature control to the hottest position.
9. Start the engine.
10. Set the blower speed to HIGH 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. Wear safety goggles and latex gloves.



14. Drill a 3-mm (1/8-in) hole in the blower case. Position this hole:

•	3.2 cm (1.25 in) from the edge (2) of the case

•	3.2 cm (1.25 in) from the bottom (2) of the case

15. Cover the carpet area underneath the evaporator case with a shop rag in order to collect any deodorizer liquid that may spill.
16. Insert the extension tube into the hole past the mark on the tube.
17. With the blower on HIGH for 5 minutes, spray the A/C deodorizer. Spray the deodorizer in short bursts, and vary the direction of the tube.
18. Turn the blower speed to the OFF position.
19. Turn the ignition switch to the LOCK position.

Wait 5 minutes.

20. Seal the hole with RTV Silicone Rubber Sealant, GM P/N 12345739, or with the equivalent.
21. Start the engine.
22. Set the blower speed to HIGH for 20 minutes.
23. Turn the ignition switch to the LOCK position.