Table of Contents
Advertisement
DESCRIPTION OF COMPONENTS
The descriptions below are various functional components
that affect the operation and shutting down of this furnace.
Some of these components and their locations are shown
in Figures 45 and 46 (page 47). If any component of the
furnace must be replaced, use only factory authorized
replacement
parts specified in the Replacement
Parts
List provided online.
Blower Limit Switch
The Blower switch prevents furnace operation when blower
is not operational.
Condensate
Drain Switch
The Condensate Drain Switch will shut down the furnace
if the condensate drain from the Collector Pan becomes
clogged.
Flame Sensor
The flame sensor verifies when a flame has carried over
from the igniter to the opposite end burner. If no flame is
detected, the furnace will shut down within 4 seconds.
Flame Roll-Out Switch
The flame roll-out switch verifies that the burner flames
are drawn into the heat exchanger tubes. If the burner
flames are not properly drawn into the heat exchanger, the
flame roll-out switch will close the gas valve and initiate
the shutdown cycle.
Gas Valve
The gas valve controls the flow of gas to the burners.
When the gas valve is energized it automatically
opens
and regulates the gas pressure in the manifold.
Inducer Assembly
The inducer assembly vents products of combustion to
the outside.
Pressure
Switch
The pressure switch verifies that the inducer is drawing
the combustion
gases through the heat exchanger. If
the flame is not properly drawn into the heat exchanger
tube, the rollout switch or the flame sensor will shut the
furnace down.
Supply Air Limit Switch
The supply air limit switch prevents the air temperature
leaving the furnace from exceeding the maximum allowable
outlet air temperature.
TROUBLESHOOTING
If the furnace fails to operate check the following:
= Is the thermostat operating properly?
= Are the blower compartment door(s) in place?
= Is the furnace disconnect closed?
= Has the circuit breaker tripped orthe control board fuse
burned open?
= Is the gas turned on?
= Are any manual reset switches open?
= Is the filter dirty or plugged?
= Is the flame sensor coated? Remove and clean with
steel wool. (Do not use emery cloth or sandpaper!)
= Is there blockage in the condensate drain switch? Also
verify that there is no double trapping of condensate.
= Is the secondary heat exchanger free of debris and
clogs?
= Is evaporator
coil
clean
and
free
of debris
(if applicable).
= Are all the LED's on the furnace control board constantly
ON? If not, refer to Table 7 orthe wiring diagram (Figure
40, page 39) to determine fault condition.
IMPORTANT NOTE: The furnace will lock out after 5
failed attempts
for ignition and will try again every
hour if the call for heat remains.
If the Inducer Blower is operating, and items above
have been verified, check the blower limit switch and
reset if necessary. See Figure 45 or 46 (page 47) for
component location.
If the furnace operates when the blower limit switch is
reset, contact a qualified service technician to identify
and repair the problem.
If the furnace still doesn't operate, check the flame roll-
out switches (Figure 45 or 46) and reset if necessary.
If the furnace operates when the flame rollout switch is
reset, contact a qualified service technician to identify
and repair the problem.
!iiiii_i1iIiiIHii!iiiiiiiiiiiiiiii!!iiiiiiiii_i_iiiii_iiiiiiii_!!iiiiiii_!_i?ii_ii1ii_iiiiiii_iii1i_iiIiIiii`iii_ii_i_i_i_i_iii1ii_iiiiii?_iiiiiiiii1iIiiIiiiii_i_fiiiiiiii_i_ii1iii1iiiiiiii1iiiiiii1iiiiiii1iiii
Control Fault (No Power)
L1/Neutral Polarity Fault
1 Hour Lockout
Normal Operation
Pressure Switch Closed Fault
Pressure Switch Open Fault
Open Limit Switch Fault
Motor Fault
Low Flame Sensor Signal
Flame Present
ii:i:iii!i
Off
Flash
Off
Flash
Alternating
Flash
On
On
On
Flash
Flash
On
Flash
Off
On
Off
Continuous
Flash
On
Table 7. Control Board Fault Codes
34
Advertisement
Table of Contents
