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2.8 Defrost Cycle
The defrost heater is controlled by the control module, which switches it via a relay. The defrost
interval can vary from between 12 hours to 22 hours of compressor run time, depending on the
duration time of the last defrost.
When the control module switches the compressor off for the defrost, there is a 2 minute delay
(warm up time) before the defrost element is turned on. The defrost is terminated when the defrost
sensor reaches +8º C. Then there is a 4 minute delay (drip time) after the defrost element has
been switched off before the compressor is turned on and the system is back to normal run.
Defrost Cycle
Compressor switches off Defrost element switches off at 8º C
Defrost element Compressor switches
Switches off back on
2 minute 4 minute
delay delay
30 minute maximum defrost time
Normal Run Warm up Defrost Cycle Drip Time Normal Run
Time
2.9 Fault Alarm
If the control module detects a fault, which it is unable to correct, an alarm is sounded. When the
cabinet has a fault, the alarm will sound a fault code each time the door is opened. The number of
beeps indicates the fault code. If the door is closed, the alarm discontinues until the door is
opened again. To repeat the fault code, close and open the door.
2.10 Compressor Starting
The compressor is started by the control module through the PTC (relay) fitted to the compressor.
It is a timed start, therefore if the compressor does not start within 1 second, the controller will
cancel the start. If the compressor draws too much current, the overload will activate and cut
power to the compressor.
3 FAULT CODES
If a fault should develop in the temperature measuring system, defrost system, temperature control
variable resistor, or should the compressor fail to start, an audio fault alarm will sound when the
door is opened. The alarm consists of a number of beeps emitted by the beeper located in the
control module. The number of beeps emitted indicates the fault code as shown in the Fault Code
table below.
3.1 Fault Code Table
Fault 2: 2 beeps
Reason: Defrost sensor failed to reach +8º C within 30 minutes. This has happened in
the last three defrosts, therefore probably defrost heater failure.
Action: Check connections at the control module and inline connectors.
Check defrost heater. If faulty, replace.
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