WD Catalog 2018

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3-5 - -
Heater Components and Controls
4. Hoses and Fittings
Heater hoses are usually 5/8", but may be 3/4" or 1" sizes. The heater inlet
hose may be smaller or the same size as the heater outlet hose. Hoses are
usually held in place by clamps. Some water valves shunt excess flow or
pressure back to the coolant return hose, assuring full flow of coolant and
relieving pressure on the valve.
5. Controls
The controls allow the operator to turn the heater on and off and regulate
the direction and quantity of warm air flow. Figure 3-7 shows a typical
heater control panel.
HOT TEMPERATURE
CAB AIR DIRECTION
COOL
DEF
FAN
OFF
BLOWER MOTOR
SWITCH
HEATER WATER
VALVE CONTROL
DEFROSTER DUCT
DOOR CONTROL
When you turn the system on, the water valve opens to allow hot engine
coolant to flow through the heater core. The blower motor circulates cab
air through the heater core to warm the air. Water valves may be cable or
air operated. Figure 3-8 illustrates both types.
Figure 3-6
These illustrations show a
single shaft motor, double
shaft motor, double and
single entry blower wheels
and a four-bladed fan.
SINGLE SHAFT
MOTOR
DOUBLE SHAFT
MOTOR
DOUBLE ENTRY
BLOWER WHEEL
FOUR BLADED FAN
Figure 3-7
This heater control panel
includes water valve, de-
froster duct, and blower
motor controls.
SINGLE ENTRY
BLOWER WHEEL