TROUBLESHOOTING
20
Symptoms
Green
LED Code
Amber
LED Code
Red
LED Code
Fault Description
Check
Cautions
•Furnace fails to operate
•Control board LED is off •None
•None
•None
•Defective disconnect switch
•defective door switch • No
115 volt power •No 24 volt
power
•Determine cause and restore
proper high and low volt power
supply
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace is waiting for a
call
•Solid ON
•None
•None
•Furnace is not receiving a
call
•None Required
•Confirm electrically safe
condition before
proceeding with work
•Furnace fan only is
running
•Rapid Flash •None
•None
•Furnace is receiving a call for
fan (24 volts on G terminal
•None Required
•Confirm electrically safe
condition before
proceeding with work
•Normal operation with
low stage call for cooling
(Ylo & G)
•One
repeating
flash
•None
•None
•Normal operation with low
stage call for cooling (Ylo & G) •None Required
•Confirm electrically safe
condition before
proceeding with work
•Normal operation with
high or single stage call
for cooling (Y & G)
•Two
repeating
flashes
•None
•None
•Normal operation with high
or single stage call for cooling
(Y & G)
•None Required
•Confirm electrically safe
condition before
proceeding with work
•Normal operation with
low stage call for heat
(W1)
•None
•One
repeating
flash
•None
•Normal operation with low
stage call for heat (W1)
•None Required
•Confirm electrically safe
condition before
proceeding with work
•Normal operation with
high or single stage call
for heat
•None
•Two
repeating
flashes
•None
•Normal operation with high
or single stage call for heat
•None Required
•Confirm electrically safe
condition before
proceeding with work
•Furnace does not
operate, three Amber
flashes on control board
•None
•Three
repeating
flashes
•None
•W2 call present without W1
•Faulty thermostat or
thermostat wiring or
improperly connected
thermostat wires
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, four Amber
flashes on control board
•None
•Four
repeating
flashes
•None
•Ylo or Y call present without
G
•Faulty thermostat or
thermostat wiring or
improperly connected
thermostat wires
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, rapid Amber
flashes on control board
•None
•Rapid
•None
•Low flame sense current
•Dirty / coated flame rod, poor
flame, improper gas pressure,
poor flame sense wire or
connections
•Clean flame rod with
steel wool. Confirm
electrically safe condition
before proceeding with
repairs
•Furnace does not
operate, one Red flash
on control board
•None
•None
•One
repeating
flash
•Flame sensed when no
flame should be present
•Gas valve stuck open,
improper wiring to gas valve,
shorted flame rod or wire
•Confirm electrical and
gas safe conditions
before proceeding with
repairs
•Furnace does not
operate, two Red
flashes on control board,
possible inducer
operation
•None
•None
•Two
repeating
flashes
•Pressure switch stuck closed
•Faulty pressure switch,
pressure switch wires shorted,
control board inducer relay
stuck closed
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, three Red
flashes on control board
•None
•None
•Three
repeating
flashes
•Low fire pressure switch
stuck open
•Faulty pressure switch,
pressure switch or tubing or
wiring / connection, control
board inducer relay failed, vent
pipe restriction / excessive
elbows or length
•Confirm electrically safe
condition before
proceeding with repairs
