In this troubleshooting situation you have been called to a restaurant to check an ice machine that, according to the customer’s complaint, “isn’t working like it should.” When you arrive, you discover that you’re dealing with a 240-volt, single-phase machine that has a remote condenser, and it also employs a small air compressor to momentarily provide air that assists in freeing the cubes from the evaporator in the harvest mode. The wiring diagram (click here for schematic diagram) shows you the electrical system.

Upon your initial evaluation of the machine, you find:

1. The refrigeration system is operating properly, and the unit has no problem manufacturing cubes.

2. There is no problem with the quality or the filtration of the water supply to the machine.

Upon further review of the schematic diagram and the equipment, you note:

1. This model of machine employs a series of relays that make and break circuits to various components during the freeze and harvest cycles.

2. During the harvest sequence implemented by the control board, the water purge, water pump, harvest valve, water valve, dump valve, and contactor control system function normally.

3. There is no air from the air compressor, and no voltage is read at any time at the 25/26 connector.

Your troubleshooting question: Which component needs to be replaced?

Compare your answers with ours by clicking on the PDF link below.

Publication date: 1/5/2015

PDF - January Troubleshooting Answer

For information on Jim Johnson’s HVACR technician training DVDs, go to

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