Fault 1 

Open circuit in 12 volt supply to Trinary switch relay RL1 inactive

Symptom 

Compressor clutch does not cut in

Fault 2

Open circuit in evaporator fan speed circuit causing the fan not to work on second speed

Symptom:

Second speed of evaporator fan not working

Fault 3

Short circuit causing evaporator fan to run continuously

Symptom

Evaporator fan will not switch off

Fault 4

Fault in temperature control circuit symptom compressor will not cut out once engaged

Symptom

Temperature control only works in one position and then will not switch off causing pipe work to freeze back

Fault 5

Condenser fan will not operate, N.B. Trinary switch should cut compressor out between 24 & 26 bar.

Symptom

Condenser fan not working causing an increase of pressure on the high side and the system is shut down by the trinary switch overload.

Fault 6

Evaporator fan will not operate causing pipe work to freeze back.

Symptom

Evaporator fan not working causing low side to drop in pressure and temperature control not to operate correctly. Pipe work will also freeze back.

Fault: 7

Close shut off valve to simulate a blocked orifice in the expansion valve.

Symptom

Valve shut off simulating a blocked orifice, the low side pressure drops to zero and the compressor overloads.