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vice, you will have ready access to the
information needed by your service
representative.
This furnace has an LED operation
and fault code display to aid the
installer, service technician, or home-
owner while installing or servicing the
unit. The LED code can be seen by
removing the access door and viewing
LED(s) through the view port in the
blower access panel.
NOTE: Removing the blower access
panel or turning off the 115-v electrical
power supply will terminate LED diag-
nostic code display.
To decipher the meaning of the LED
code, and suggested action, the follow-
ing cross-reference can be used.
MODEL 345MAV DIAGNOSTIC CHART
(See Fig. 2.)
NOTES:
1. Light on continuously means control has power and working properly.
2. The fault code is a 2 digit number. The first digit is determined by the number of short flashes of the light and the second digit is determined by number of long
flashes of the light.
FAULT
CODE FAULT CODE DESCRIPTION CHECKLIST
13 or 33 Limit Switch Lockout
Check for dirty air filter.
Check for blocked return-air or supply-air grilles.
14 or 34
Ignition Lockout or
Ignition Proving Fault
Check to be sure manual shutoff valve in gas supply pipe is in the open position. (Follow
start-up procedure if you open gas line.)
NOTE: Turn off the electrical supply and remove access doors before continuing with this
checklist.
Check to be sure control switch or knob on gas valve is in ON position. (Follow start-up
procedures if you must reset switch or knob to ON position.)
24 Furnace Fuse Open Check for blown fuse and possible short in 24-v wiring.
31 Pressure Switch Not Closed
Check to make sure that all PVC pipes leading into the combustion-air intake and vent/
exhaust are free from any cracks and sags. Also check the combustion-air intake adjacent to
the furnace and vent/exhaust pipe on the outside of your home for blockage.
12, 21, 22,
or 23
Any Other Fault Code Call dealer for service.
No Fault
Code
Signaled
Furnace Fails to Operate and No
Fault is Signaled
Check thermostat for proper temperature setting.
Check for blown fuses and circuit breakers.
Check to be sure blower access panel is properly in place.