SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: (F/G)9MVE
Specifications subject to change without notice.
440 04 4801 03 28
Figure 17 Troubleshooting Guide − Flow Chart
Is AMBER LED status light ON solid,
alternately flashing bright-dim-bright-dim
like a heartbeat, or flashing ON and
OFF?
Is there 24V at SEC-1 and SEC-2?
Is there 115V at L1 and L2?
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 AMBER 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 is the number of
long flashes?
The last status code has cleared. To
recall a previous status code disconnect
the R thermostat connection, reset
power, and put setup switch SW1-1 in
the ON position. The AMBER LED will
flash the status codes in the order of
occurrence. Record status codes until
heartbeat flashes. After heartbeat
flashes several times the status codes
will repeat. Status codes are erased
after 72 hours or can be manually erased
by putting setup switch SW1-1 in the ON
position and jumpering R, W/W1, and
Y/Y2 simultaneously until the heartbeat
flashes. When done put setup switch
SW1-1 in the OFF position.
Was there a previous status code other
than the heartbeat?
Go to section below for the status code
that was flashed.
Does the control respond to W/W1, W2,
Y1, Y/Y2, and G (24V) thermostat
signals?
Run system through a low-heat, high-
heat, or cooling cycle to check operation.
Status codes are erased after 72 hours
or can be manually erased by putting
setup switch SW1-1 in the ON position
and jumpering R, W/W1, and Y/Y2
simultaneously until the heartbeat
flashes.
Is 24V present at W/W1, W2, 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
resistor, connect the Com24V thermostat
terminal to the thermostat, or replace the
thermostat.
YES
NO
YES
YES
YES
YES YES YES
YES
START
YES
YES
NO
NO
NO
NONO
NO
NO
NO
YES
NO
NO
Troubleshootin
Guide
Replace furnace control.
YES
Replace fuse then disconnect thermostat
leads to isolate short circuit.
NO
Is AMBER LED status light ON solid?
NO
YES
Check to make sure that the correct
model plug PL4 is installed. The wiring
schematic shows all valid model plugs.
Is the correct model plug installed?
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.
YES
Replace model plug PL4.
NO
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