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| Illustration 1 | g00296414 |
(1) Filter (2) Evaporator (3) Heater core (4) Blower (5) Blower motor (6) Electrical harness (blower motor) (7) Pipe (outlet for engine coolant from heater) (8) Cable (sensor for the evaporator) (9) Sensor (evaporator) (10) Valve (inlet for engine coolant to heater) | |
The heating system provides warm air to the operator's compartment for purposes of heating and defrosting.
The heating system uses coolant from the engine cooling system. Water valve (10) is controlled by a temperature control lever on the control panel in the cab. With the temperature control lever in the OFF position, water valve (10) is closed. The closed water valve prevents the flow of coolant through heater core (3). The water valve is actuated when the operator moves the temperature control lever to the desired temperature. When water valve (10) opens, warm coolant flows from the engine to heater core (3). As the warm coolant flows through heater core (3), the temperature of the air flow across the core increases.
The amount of increase in air temperature is controlled by the amount of coolant that flows through heater core (3). As the amount of coolant increases, the temperature of the air that flows across heater core (3) increases. The coolant flows from heater core (3) back through the engine cooling system.
Heater Core
The heater core is a heat exchanger. The heater core circulates engine coolant in order to increase the temperature of the air inside the cab. The heater core is constructed of copper and tin. The heater core is made of flat tubes. Copper and tin are utilized in the design because these metals are excellent conductors of heat. The heater core and the water valve are connected with a heater hose. These connections should be checked for leaks periodically. The water valve controls the amount of engine coolant that flows into the heater core. Foreign matter on the outside surface of the heater core can cause a poor transfer of heat. The heating system loses the capability to heat when the heater core is dirty. The outside surface of the heater core should be cleaned when the system is checked.