Furnace Fails to Operate Properly
Review "Sequence of Operation" and visually inspect the
following before troubleshooting:
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
Is the integrated ignition/blower control board and power to
the furnace on?
Is the blower compartment door securely closed?
Are the manual shutoff valves in the gas line to the furnace
Are all wiring connections secure?
Start the system by setting thermostat above the room
temperature. Observe system response. Then use the
information provided in this section to check the system
Fault Code History Button
The control stores the last 5 fault codes in memory. A push-
button switch is located on the control. When the push-button
switch is pressed and released, the control flashes the stored
fault codes. The most recent fault code is flashed first; the oldest
fault code is flashed last. To clear the fault code history, press
and hold the push-button switch in for more than 5 seconds
The furnace has a built-in, self-diagnostic capability. If a system
problem occurs, a failure code is indicated by the LED on the
ignition control board. The control continuously monitors its own
operation and the operation of the system. If a failure occurs, the
LED will indicate the failure code.
IMPORTANT: Do not remove the blower compartment door or
turn off the power to the furnace since either action will clear the
control's memory of the fault.
1. Start the system by setting the thermostat above the room
2. Observe the system's response.
3. Use the information provided in this section to check the
Failure Codes Chart
No power to control or control hardware fault
Flame present with gas valve off
Pressure switch closed with inducer off
Pressure switch open with inducer on
High limit switch open
Rollout switch open
Pressure switch cycle lockout
Lockout due to no ignition
Lockout due to too many flame dropouts
Incorrect line voltage phasing