56
TROUBLESHOOTING
Symptoms
Green
LED Code
Amber
LED Code
Red
LED Code
Fault Description
Check
Cautions
•Furnace does not
operate, four Red
flashes on control board
•None
•None
•Four
repeating
flashes
•Open limit circuit, main
limit, aux limit, or roll out
switch
•Temperature rise, duct static,
gas pressure, burner alignment,
orifice plate position, wiring to
all limits
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, five Red
flashes on control board
•None
•None
•Five
repeating
flashes
•Limit & rollout circuit open
for 15 minutes. Open control
board fuse or rollout switch
•Control board fuse,
Temperature rise, duct static,
gas pressure, burner alignment,
orifice plate position, wiring to
all limits
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, six Red flashes
on control board
•None
•None
•Six
repeating
flashes
•Pressure switch cycling
lockout, pressure switch has
opened 5 times in the same
heating cycle
•Excessive venting restriction,
leaking pressure switch tubing
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, seven Red
flashes on control board
•None
•None
•Seven
repeating
flashes
•Lockout - excessive retries
from flame not being proven
during trial for ignition
•Gas pressure, gas valve, front
cover pressure switch, flame
rod
•Confirm electrical and
gas safe conditions
before proceeding with
repairs
•Furnace does not
operate, eight Red
flashes on control board
•None
•None
•Eight
repeating
flashes
• Lockout - excessive recycles
from flame proving being lost
after being proven
•Gas pressure, gas valve, front
cover pressure switch, flame
rod
•Confirm electrical and
gas safe conditions
before proceeding with
repairs
•Furnace does not
operate, nine Red
flashes on control board
•None
•None
•Nine
repeating
flashes
•Improper grounding or
reverse polarity
•115 volt hot & neutral supply
to furnace reversed, hot wire
(door switch & L1 on control
board) must read 115 volts to
ground & neutral. Neutral wire
should measure 0 volts to
ground
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, ten Red flashes
on control board
•None
•None
•Ten
repeating
flashes
•Gas valve current detected
with no call for heat
•Verify gas valve is not
receiving voltage from an
electrical short. If valve wiring
is correct replace control board
•Confirm electrical and
gas safe conditions
before proceeding with
repairs
•Furnace does not
operate, eleven Red
flashes on control board,
inducer running
•None
•None
•Eleven
repeating
flashes
•Open limit switch circuit for
more than 5 minutes
•Re-set main power and check
indoor blower operation
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, twelve Red
flashes on control board
•None
•None
•Twelve
repeating
flashes
•Control board igniter relay
not energizing igniter
•Replace control board
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, control board
Red LED on solid
•None
•None
•Solid ON
•Control board internal fault
•Replace control board
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, control board
Red LED rapid flash
•None
•None
•Rapid Flash •Twinning error
•Correct twinning wiring
•Confirm electrically safe
condition before
proceeding with repairs
•Furnace does not
operate, control board
Red LED with three
double flashes
•None
•None
•Three
double
flashes
•Second stage pressure
switch stuck open
•Verify pressure switch
function & tubing, verify
inducer operating and pulling
enough vacuum to engage
switch
•Confirm electrically safe
condition before
proceeding with repairs
