In this month’s troubleshooting situation, you are dealing with a 4-ton split system, and the locale is a desert Southwest city. The customer in this case is the landlord, and they are working on the residence, getting it ready to rent after the departure of a long-term tenant. Their description of the problem is that the house “just won’t get comfortable.”

When they called, they asked for an estimate of what it would cost to get a ”Freon” charge because they knew that the system had never been serviced since it was installed. They also told the dispatcher that the day before, when they decided to check the filter, they found that there wasn’t one in place, so they installed a new one. 

When you arrive, you check the ambient temperature with your digital meter, and it shows 95°F. Your initial indoor checks confirm that the temperature in the building is uncomfortable — above the thermostat set-point, and the indoor fan motor is operating. Moving to the outdoor unit, you note that the condenser coil is not dirty, the outdoor fan motor appears to be operating normally, and the compressor is running.

After you perform a temperature split test and find the differential lower than it should be, you decide to access the R-410A system. You find the system low side pressure to be 104 PSIG and the high side pressure is 355 PSIG (see Figure 2 for a PT Chart Reference).

At this point in your evaluation, you decide to accomplish specific checks in regard to the operation of the indoor segment of the system (Figure 1 shows the results of the tests you conducted). 

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

Compare your answer with ours here.

Publication date: 5/8/2017

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