The output sensor board is mounted directly in the outlet air opening of the heater. It controls the temperature of the outlet air and provides over temperature protection for the heater.
Power feeds from terminal block position F1 to B of the output temperature sensor board. A "Y" output from this board sends output temperature information through an PTC thermistor (temperature rise = resistance rise) to the damper control board. Power out on "R" goes through two one-time thermal limits and is the line one potential to the blower system. If one of the two thermal limits opens, it indicates an over-temperature condition.
If the output sensor opens, the discharge air temperature was above normal operating temperatures. This may be caused by one or more of the following conditions:
Failed damper control board
Blower filled with dirt and debris
Blower failed to operate in low speed
Damper is stuck or not operating properly
NOTE: If you replace an output temperature sensor board, you MUST complete the Air Discharge Check Out Procedure to determine what caused the output sensor to open.