TM 9-2320-386-10 2-77 2-29. OPERATION OF PERSONNEL HOT WATER HEATER a. Push temperature control knob (1) to CLOSED position. b. Start engine (para. 2-12) and allow engine to reach normal operating temper- ature 160°-230°F (71°-110°C). c. Pull temperature control knob (1) to OPEN position. d. Place heater switch (3) to HIGH or LOW position. e. Pull defroster control knob (2) out to defrost windows; push defroster control knob (2) in to heat cab. 3 2 1