In this month’s troubleshooting problem we have a customer who can only tell us that their heat pump “isn’t working” and “the temperature in the building isn’t right.” When you arrive, you confirm that the system isn’t operating properly. The indoor fan motor is running normally, but the building temperature is far from the thermostat set-point. Satisfied that the problem is not with the indoor section of the equipment, you focus on the outdoor unit, using the partial schematic diagram in Figure 1 to become familiar with the components and circuitry there. (Click here to access a PDF of Figure 1.)
When you evaluate the situation, you find the following: