Installation Instructions
56
T
ROUBLESHOOTING
 C
HART
Associated
LED Code
2
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










