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 discharge air sensor is used in applications where the 5100 or 7100 Series system is installed with a Steffes air handler. The error generally indicates a missing or open resistor, an open sensor, a short in the wiring, or a circuit board which is out of calibration. Normal operating range is 25°F/-3°C to 175°F/79°C
AIR HANDLER: Verify accuracy of the discharge air sensor by reading resistance across the sensor wires. Compare the sensor reading to the value in L112. Make sure the air handler wiring harness is connected properly. The harness runs from the sensor on the supply air blower assembly in the air handler to the DS and SC terminals on the terminal block (PSC) or the "Air" terminals on the LV circuit board (ECM) in the system
NO AIR HANDLER: Verify resistance on the factory installed resistor (1.2k nominal) and verify connections to the terminal block or processor control board.