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Evaporator coil blocked with
ice
1. Defective time clock
1. Replace
2. Cabinet location in store
2. Move cabinet away from
door or other source of draft
3. Defective defrost heater
3. Replace
4. Defective defrost thermostat 4. Replace
The defrost thermostat should have the defrost circuit in the
closed position when the cabinet goes into defrost. It is set to
open that circuit at 58ºF/14ºC, at which time it also energizes the
solenoid in the time clock which trips the time clock off defrost
and back into the refrigeration cycle. It must be remembered
that when checking the time clock and defrost circuit, that the
time clock can be put into the defrost cycle manually by turning
the time clock dial, but the defrost heater will not come on until
the defrost thermostat temperature has been reduced below
32ºF/ 0ºC.
Defrost cycle too long
1. Terminating on timer
failsafe. (factory set 40 mins)
1. Replace defrost thermostat
The defrost termination thermostat should terminate the defrost
when it senses 58F/-10C.
Time clock mechanism not tripping off defrost due to bad
solenoid in the time clock. If there is an open circuit in the coil
of this solenoid, it will not trip the time clock mechanism off
defrost after the defrost termination thermostat has operated.
To determine if the solenoid is good, turn the clock into defrost.
Place a jumper across X and N at the clock. If the soldnoid is
good this will trip the clock off defrost indicating that it is
working.
Adverse conditions require a longer than normal defrost. Air
currents over and into the cabinet, or a great amount of usage
during conditions of high humidity could create excessive frost.
