In this troubleshooting situation, the customer has called to report a “no heat” problem. The equipment is a 5-ton, 230 VAC single-stage gas/electric package unit that employs an integrated furnace control and a constant torque blower motor.
When you arrive, you find that the building temperature is far below the set-point of the thermostat, and the indoor fan motor is operating, but the temperature of the air being delivered from the supply registers indicates that the furnace is not operating.