Our troubleshooting situation begins with the customer’s description of the problem: “My air conditioner is blowing warm air.”
When you arrive, you confirm that the air handler on this 12-year-old, 4-ton split system is operating normally and the temperature in the building is far above the thermostat set-point. When you check the outdoor unit, you determine that this equipment is of a significant age, and based on your observation that the outdoor fan motor is operating and the compressor is off on overload, we’re showing the segment of the wiring diagram you focus on to begin your diagnosis in Figure 1. (Note: You also find that the legend for this diagram is illegible due to the age of the equipment).