TM 9-2320-209-10-1 4-16. OPERATION OF HOT WATER PERSONNEL HEATER KIT. 1. 2. 3. 4. 5. 6. 7. Start engine and let it warmup. (Refer to para 4-6b.) CAUTION In ice, snow, or 0°F weather do not damage glass by making sudden changes in temperature. Let more heated air flow to personnel compartment than to the windshield. Pull DAMPER knob (1) out to let warm air flow to personnel compartment. Pull DEFROSTER knob (2) out to let warm air flow to windshield. Move DAMPER knob (1) and DEFROSTER knob (2) in or out to control amount of warm air to windshield or personnel compartment. Set HEATER (blower motor) switch (3) in HI or LO position as needed. To stop heating or defrosting action, set HEATER (blower motor) switch (3) in OFF position. Stop engine. (Refer to para 4-6e.) 4-383