In this issue’s troubleshooting situation, the problem unit we’re facing is a reach-in refrigerator in a restaurant and the customer’s description of the problem is that they discovered spoiled food in the cabinet when they arrived early in the morning prior to opening.

When you arrive, you find that this particular unit has been in service for almost 12 years, and it employs a constant-run evaporator fan, two pressure switches for protection, and a fractional horsepower, semi-hermetic compressor that employs a potential relay, start capacitor, and run capacitor. (See the partial wiring diagram in Figure 1.)

When you open the cabinet door and re-start the unit by setting the control to an on position, you note that the evaporator fan motor operates along with the condenser fan motor, and you also note a hum and a click, accompanied by a brief dimming of the cabinet light. Checking closer, you confirm that the compressor is not starting. This prompts you to disconnect the power supply, then remove and check the compressor start components, along with the compressor motor windings, with an ohmmeter. The test results you get are as follows:

• From C to R - 2.5 Ohms

• From C to S - 6 Ohms

• From 1 to 2 - Infinity

• From 2 to 5 - 4,500 Ohms

• Start Cap - 165 MFD

• Run Cap - 15 MFD

Your troubleshooting question: Which component has to be replaced to get this unit cooling again?

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Publication date: 07/06/2009