Troubleshooting Puzzle: A Split System That’s Not Cooling
Note: Before we get into the details of this particular situation, we want to point out that there are actually three questions to answer.
In this month’s troubleshooting problem, the equipment is a split system that’s approximately 8 years old, consisting of a gas furnace that provides heat in the winter, and employs a condensing unit and “A” coil to provide summer cooling. The information you get from the dispatcher is that the customer’s complaint is that the system is not cooling and the specific information they provide is that the unit is “blowing warm air.”
Which brings us to the first question about this problem: What are two components located in the furnace assembly that can be eliminated from consideration as the possible source of the problem?
When you arrive, you confirm that the system is blowing warm air. You also confirm that the thermostat is set to the cooling mode with the set-point below room temperature, and the fan switch is set to the AUTO position. A check on the condensing unit reveals that the condenser fan motor is operating normally, but the compressor is not running. It is hot to the touch and off on internal overload.
Your second question: What two components inside the condensing unit can be eliminated from consideration as the source of the problem?
After turning off the disconnect switch and removing the access cover, you find that the compressor is hot to the touch, indicating it is attempting to start. Based on that observation, you disconnect all the appropriate wiring when necessary, and, with a digital meter, check the start components shown in Figure One. And, you get the following results:
- At terminals SC, you read the microfarad rating shown on the capacitor case.
- At terminals RC, you read the microfarad rating shown on the capacitor case.
- At the SR terminals of the potential relay coil, infinity.
- At the SR terminals of the potential relay switch, a fraction of an ohm.
Your final troubleshooting question: What do you have to do to get this unit operating again?
Submit your answer here.
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