TM-9-2320-387-10 HMMWV Operator Manual Download
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TM 9-2320-387-10 2-122 2-50. VEHICULAR HEATER OPERATION NOTE The vehicular heater is an optional kit which may or may not be installed on the vehicle. a. General. The vehicular heater is used for pre-heating and boosting the heat of the water-cooled engine. The heater works in conjunction with the heating system of the vehicle to heat driver’s cabin, passenger compartment, and to defrost windows and windshield of the vehicle. The heater operates independently of the vehicle engine. It is connected to the coolant circuit or the heating circuit, fuel supply system, and the electrical system of the vehicle. When the operating temperature has been reached, the temperature sensor will send a signal to the control unit. The heat output will then be reduced to 25 percent. Should the temperature still remain at the upper limit, the heater will turn off, but the coolant pump will remain running. The heater will automatically restart once the system temperature has dropped to the lower switch point of the sensor. .WARNING. • Do not operate the vehicular heater in a closed area without proper exhaust evacuations. Damage to heater or injury to personnel may result. • Do not operate the vehicular heater when refueling. Damage to heater or injury to personnel may result. NOTE • After shutting off the on/off switch there is a cool down period of 90 seconds. The blower and coolant pump works for 90 seconds to purge the heater. • DFA fuel should be used at temperatures below -40°F (-4°C). b. Operation. (1) Activate heater by moving on/off rotary switch (1) on the vehicle control panel (2) to ON. (2) A green light (3) on on/off rotary switch (1) indicates heater is in operation. (3) If, during heater operation supplied voltage drops below 10.25 + 0.5/20.5 + 1.0 V for more than 20 seconds, fault lock out will occur and the heater will switch off. If this happens, notify unit maintenance.