TM 10-3930-669-20 2-14.  ELECTRICAL SYSTEM TROUBLESHOOTING (CONT). 17.  HEATER BLOWER DOES NOT OPERATE. INITIAL SETUP Tools and Special Tools Tool Kit, General Mechanic's: Automotive (Item 1, Appendix B) Multimeter (Item 2, Appendix B) STE/ICE-R (Optional) (Item 14, Appendix B) References TM 10-3930-669-10 Equipment Condition Engine OFF (TM 10-3930-669-10) MAIN POWER switch OFF (TM 10-3930-669-10) Parking brake applied (TM 10-3930-669-10) Wheels chocked (TM 10-3930-669-10) KNOWN INFO 24 vdc circuits operate. POSSIBLE PROBLEMS Fuse 9 faulty. Wire 38 faulty. Heater blower switch faulty. Blower motor ground wire faulty. Fan blower motor faulty. TEST OPTIONS Visual test. REASON FOR QUESTION If element is broken, fuse 9 is faulty.  If fuse 9 is OK, wire 38 is faulty. 2-218