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506650−01
Demand Defrost Control (A108)
The demand defrost control measures differential temperatures to detect when the system is performing poorly because of
ice build−up on the outdoor coil. The controller
self−calibrates
when the defrost system starts and after each system defrost
cycle. The demand defrost control components are shown in figure 22.
24V TERMINAL STRIP CONNECTIONS
DIAGNOSTIC LEDS
PRESSURE
SWITCH
CIRCUIT
CONNECTIONS
TEST PINS
Note − Component locations vary
by board manufacturer.
SENSOR PLUG IN (COIL &
AMBIENT
SENSORS)
REVERSING VALVE
DELAY PINS
LOW AMBIENT THERMOSTAT
PINS
DEFROST TERMINATION PIN
SETTINGS
Figure 22
.
Demand Defrost Control (A108)
