TM 10-3930-669-20 2-14.  ELECTRICAL SYSTEM TROUBLESHOOTING (CONT). 18.  HEATER BLOWER DOES NOT OPERATE IN HIGH 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) NOTE The  following  procedure  covers  HIGH  position,  but  the  general  steps  can  be  used  for  LOW position. KNOWN INFO Heater operates in LOW. POSSIBLE PROBLEMS Heater blower switch faulty. Lead wire 4 faulty. Fan blower motor faulty. TEST OPTIONS Continuity test. STE/ICE-R #91. REASON FOR QUESTION If continuity is not present, heater blower switch is faulty. 2-224