Installation Manual
440 01 4501 01 75
Specifications subject to change without notice.
Is LED status light ON solid, alternately 
flashing bright
-dim-bright-dim like a 
h
eartbeat, or flashing ON and OFF? 
Is there 24V at 24VAC and COM? 
Is there 115V at L1 and NEUTRAL? 
Is the 24V fuse open? 
Is door switch closed?  
Replace transformer. 
Replace door switch. 
Is there 115V going to switch?  
Close the door switch.  
Is circuit breaker closed?  
Check for continuity in wire from circuit 
breaker to furnace. 
Close circuit breaker and go back to 
START. 
Is LED status light alternately flashing 
bright
-dim-bright-dim like a heartbeat? 
Determine status code. The status code 
is a 
single or two digit number with the 
first 
number 
determined by the number of 
short flashes and the second 
number 
after 
the plus (+) sign, the number 
of long 
flashes. 
To recall a status code: Briefly (2 ā 3 
seconds) connect the
 TEST/TWIN terminal 
to the āCā thermostat terminal with a jumper 
wire 
to begin status code recovery and 
component test. If a previous status code is 
present, the code will repeat 4 times then 
go on to component test. If no previous 
code is present, a component test will 
begin without flashing any status codes. 
Component Test Sequence: Gas valve 
and humidifier will not be turned on. 
Inducer motor will start and remain on until 
the end of the blower test, then off. T
he 
following components are on for 10 ā 15 
seconds each individually: hot surface 
igniter, 
blower speeds: FAN (if present), 
HEAT, COOL. 
Was there a previous status code? 
Go to section below for the flashed status 
code. 
Does the control respond to W, Y1, Y/Y2, 
and G (24V
) thermostat signals? 
Run system through a heat, or cooling 
cycle to check operation. Status codes 
are erased after 72 hours.
Is 24V present at W, Y1, Y/Y2 or G 
thermostat terminals on the furnace 
control?
Check room thermostat or 
interconnecting cable.
Disconnect all the thermostat wires from 
the furnace control.
Does the problem repeat when using a 
jumper wire?
Replace furnace control. 
The thermostat is not compatible with the 
furnace control. Either install a ballast 
r
esistor, connect the C furnace control 
thermostat terminal to the thermostat, or 
replace the thermostat.
YES 
NO 
YES 
YES 
YES 
YES 
YES 
YES 
YES 
START 
YES 
YES 
NO 
NO 
NO 
NO 
NO 
NO 
NO 
NO 
YES 
NO 
NO 
Troubleshooting Guide 
Replace furnace control. 
YES 
Inspect secondary voltage (24V) wiring, 
including thermostat leads for short 
circuit.
Replace fuse
NO 
Is LED status light ON solid?  
NO 
YES 
The control is locked out and will auto-
reset after 1 hour. Lockout could be due 
to any of the following:
-
  Flame sense circuit failure. 
-
  Gas valve relay stuck open. 
-
 Software check error. 
Reset power to clear lockout.  Replace 
control if code repeats. 










