Hygena APM6855 – Defrost Fault.

[mystick]

I have a 13month old APM6855 which has developed a fault with its defrost cycle. I would like to test the thermistors, heating element and defrost timer and any inline fuses however in the absense of a service manual/wiring diagram I’m having a little trouble identifying the specific components.

I would like to know if this model has a mechanical timer or an electronic timer for the defrost cycle and what the two ITW ISPRA Black switches on the Freezer Element are for.

Any enlightenment would be great as the Appliance Engineer who turned up last week took one look at the freezer unit and said it was too difficult to access/test due to the insulation around the freezer unit- surely with a little time and effort it can be tested to find the faulty component.

Thanks
Regards
Mystick

[mystick]

Since my last post, I have guessed that the two ISPRA Black switches are in fact probably fuses in series with the heating element (one on the live and one on the neutral) Both appear to be ok. The heating element impedance is approx 3.5kOhm (The fact that there is continuity suggests the element is ok)

There is a thermistor which lies behind the freezer coils it also measures about 3-4 kOhms I would think this is ok (I had expected this to be a thermostat either open or closed but it seems that this thermistor must control a switch on the electronic board – how I wish I had a schematic for this). My thoughts are if the heating element impedance appears ok then the electronic board/timer has gone faulty.

I would appreciate your on how to assess further and how much a new electronic board/defrost timer unit would be.

Thanks
Regards
Mystick

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