SUMMIT-MULTI – INSTALLATION/OPERATION MANUAL
5IM-OF-K6C0-01
Jun/11
19
9.2 MAX/EVO SENSOR DIAGNOSTICS
SENSOR FAULT ON EVO FURNACE
The 9200i control will only indicate heat sensor trouble with three RED flashes of the LED on
the circuit board and a solid GREEN LED, if the sensor is suspect. The 9200i control will NOT
indicate a fault in the AC/Aux sensor. Check all sensor cable connections to ensure contact is
made. To clear a fault from the circuit board, remove power momentarily, this resets the
control.
If the AC/Aux sensor is bad, the 9200i control will operate the blower with a timed ramped up
and ramped down blower speed during the call for furnace operation on the “Y” terminal. If the
AC/Aux sensor is suspect then check sensor as below.
SENSOR FAULT ON MAX FURNACE
If the AC/Aux sensor is bad, the 9300i control will indicate heat sensor trouble with three RED
flashes of the LED on the circuit board and a solid GREEN LED. Check all sensor cable
connections to ensure contact is made. To clear a fault from the circuit board, remove power
momentarily, this resets the control.
If the original jumper for this sensor plug on the board is with the furnace, plug it in to the circuit
board in the “COOL” circuit board plug. If the 9300i control operates normally in the heating
mode without any faults then check the AC/Aux sensor. If there is still a sensor fault, then
check the heat sensor.
HEAT SENSOR CHECK
You can check the HEAT sensor by reading the ohm’s between the center wire connection on
the plug and the two outside wire connections on the plug at the board (the plug should not be
connected to the board). The ohm reading should be approximately 5 k ohms for 77°F (25°C);
the reading may be slightly higher or lower depending upon the sensor temperature.
If the ohm reading is infinity the sensor or wires are broken, if the reading is ZERO then there
is a short on the sensor or wires. When checking between the two outside wire connections
on the plug the ohm reading will be double of that between the center and an outside wire
connection.
If there is a fault you should disconnect the cable at the sensor and recheck the sensor to
ensure that there is not a break in the cable.
AC/AUX SENSOR CHECK
You can check the AC/Aux sensor by reading the ohm’s between the two wire connections on
the plug at the board (the plug should not be connected to the board). The ohm reading
should be approximately 5.7k ohms for 77°F (25°C); the reading may be slightly higher or
lower depending upon the sensor temperature.
If the ohm reading is infinity the sensor or wires are broken, if the reading is ZERO then there
is a short on the sensor or wires.
If there is a fault you should disconnect the cable at the sensor and recheck the sensor to
ensure that there is not a break in the cable.
If the sensor is found to be faulty then replace the appropriate sensor.
