Patience is a virtue when you’re troubleshooting a refrigeration system. It is important for you not to rush to a quick diagnosis.

A practice I have used is to leave my tools in the service vehicle upon arriving at a call. I walk onto the job with only a good-quality flashlight in hand. I speak to the customer, visually inspect the equipment, and evaluate potential causes.


Some questions you may ask the customer include:

  • How old is the unit?

  • When was the last time it was repaired and what was done?

  • Has the unit been working OK up until the time of the breakdown?

  • Have you noticed strange sounds or erratic operation lately?

    Your customer’s answers can give you important information you may not find during the equipment inspection. For example, if refrigerant was added to the system a short time ago but no one took the time to look for or repair leaks, it is likely that the refrigerant has leaked out again.

    Another example: Your customer says that during the last day or two, that the unit seems to have been running all the time. Some items in the cooler were frozen and the temperature in the cooler rose. This could be caused by a defective thermostat.


    Visually inspecting the equipment is an important part of troubleshooting. During my initial visual inspection, I try to determine:

  • The type of metering device used;

  • The type of refrigerant in the system;

  • The condition of evaporator and condenser coils;

  • Required supply voltage; and

  • The equipment’s overall condition.

    Knowing the type of refrigerant used in the system helps you determine the correct operating pressure when it’s time to install a set of service gauges onto the system.

    Another part of my visual inspection is to look for oily pipes or parts. This is usually a good indication of a refrigerant leak.

    Your initial inspection of the evaporator and condenser coils is critical. An iced-up evaporator coil and dirty condenser coil are two common problems; they can easily be identified during a visual inspection. The cause may not be apparent, but the symptom is easy to discover.

    Knowing the correct supply voltage — including whether it is a single- or three-phase system — will also help you later on, when it’s time to measure the supply voltage.

    I also feel the head of the compressor to find out if it’s cold, warm, or hot. This helps me determine if the compressor is the cause of the problem. For example, if the compressor is extremely hot and not running, it may be off on an overload.

    Visually inspecting all of the major components takes a little extra time, but it is time well spent.

    Marchese is owner of Coldtronics of Pittsburgh, PA. He can be reached at 412-734-4433; (website); or (e-mail).

    Publication date: 07/01/2002