It’s the middle of summer and your customer, who can’t provide you with any helpful information about the history of this situation since they just recently purchased the business, is complaining that the temperature inside their small convenience store won’t get comfortable whenever the outdoor temperature gets over 90°F. The equipment is a three-phase, 5-ton rooftop unit (see figure one), and when you evaluate the operation of the system, you find the following:

  • A visual inspection of the filters and coils proves that they are clean, and there is water in the condensate drain pan;
  • An accurate check of the supply air shows it to be 65° dry bulb;
  • The liquid line sight glass is clear and the oil level in the compressor is at ½ the sight glass;
  • Both the condenser and evaporator fan motors are operating normally.

You also note that after several hours of continuous operation, all system components remained relatively unchanged. All continued to operate and none shut down on any safeties.

Your troubleshooting question: What is the next step you need to take in regard to this situation?

Compare your answers with ours here.

Publication date: 3/6/2017

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