THIS PROCEDURE MUST BE PERFORMED BY A QUALIFIED TECHNICIAN.
THIS PROCEDURE MUST BE PERFORMED BY A QUALIFIED TECHNICIAN.
Er04 indicates the discharge air sensor temperature is out of normal operating range. The error generally indicates a sensor that has lost accuracy, a short in the wiring, open wiring, or a circuit board which is out of calibration. Normal operating range is 25°F/-3°C to 175°F/79°C. Verify accuracy of the discharge air sensor by reading resistance across the sensor wires. Compare the sensor reading to the value in Location 112 (L112) which is a direct reading of the discharge air temperature. Make sure the discharge air sensor wiring harness is connected properly. The harness runs from the sensor on the supply air blower assembly to the brown wires on the 15-pin harness on the control board (PSC-style) or the "Air" terminals on the Low Voltage circuit board. The sensor is not polarity sensitive.
02/21/2022 Rev 2