Air Conditioning and Heating R-12 All Caterpillar Machines – Heating System Schematic



Illustration 1 g00343853

Heating System

(1) Heater coil

(2) Heater Control Valve

(3) Outlet supply connection for the coolant

(4) Return connection for the coolant

The heating system uses the coolant from the engine cooling system. The heater control valve (2) is connected to the temperature control knob in the cab. With the temperature control knob in the OFF position, the heater control valve prevents the flow of the coolant through the heater coil (1). When the control knob is moved from the OFF position the control valve (2) will open. The control valve allows coolant that is warm to flow from the outlet (3) through the control valve (2) to the heater coil (1). As the warm coolant flows through the heater coil, the temperature of the air flow across the heater coil increases.

The temperature of the heater is controlled by the amount of coolant that flows through the heater coil. The increase of the coolant flow through the heater coil will increase the temperature of the air that flows across the heater coil. The coolant from the heater coil will flow to the return connection (4). Then, the coolant is sent back through the engine cooling system.

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