dixell

[fixbear]

Never heard of a Celfrost. But I did find them and was surprised that it was a Middleby company.  But I still could not find what you listed as a model,  So I don’t know what system of wiring the evaporator they use.  So I’ll cover both methods and you can open the evap to see.

 

The first method used today is Dixel controlled Evaporator defrost with a thermister that monitors the evaporator temp and another that monitors the box temp. With this one the end of defrost is monitored and fans will not come on till the evaporator is back to freezing.  So either the coil is not getting cold, or the thermister is faulty.and not giving the controller a good reading.

 

The other method is the old mechanical defrost termination sensor attached to the evaporator is some wheres downstream of the last 1/3 of circuit on a end coil that is wired to both the heater and fan motor.  When it gets above freezing in defrost it goes open to the heater and recluses when the coil get’s back to freezing. They are made both 2 and 3 wires depending how the manufacturer wires the box. It is a bimetal switch like a klixon bu sealed and a cupped shap bottom for the coil with a clip.

 

 I would assume it is the first one due to the fan light being off.

[fixbear]

This may also help you to understand the operation of the controller.;

https://www.unicef.org/supply/files/instruction_digital_controller.pdf