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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
factory authorized replacement parts specified in the Replacement Parts List.
Flame Sensor - Verifies when a flame is present. If no flame is detected, the furnace will shut down within 4 seconds.
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 - Vents products of combustion to the outside.
Pressure Switch - Verifies that the inducer is drawing the combustion gases through the heat exchanger. The pressure
switch prevents furnace operation with excessive flue blockage or improper inducer operation.
Main Air Limit Switch - Prevents the air temperature leaving the furnace from exceeding the maximum allowable outlet air
temperature.
Temperature Limit Switch - Verifies the inducer is drawing combustion gases through the heat exchanger properly. The
temperature switch prevents furnace operation in the event of flue or combustion air passageway blockage, or improper
inducer operation. If the roll-out switch opens, the gas valve will close and initiate the shutdown cycle. The blower will run
continuously due to open limit fault.
Autotransformer
Transformer
Capacitor
Air/Fuel
Mixing Tube
Combustion Air
Orifice Plate
Compressor
Limit Switch
FURNACE COMPONENTS
Figure
14. If any component of the furnace must be replaced, use only
Furnace
Control
Board
Terminal
Strip
Gas Valve
Inducer
Assembly
Figure 14. Component Locations
Autotransformer
Fuse
Contactor
Ignitor Relay
Ground Lug
Sight Glass
Gas Burner
Head
Primary Air
Limit Switch
Pressure Switch
Ignitor/Flame
Sensor Assembly
Access
Collector
Box
29
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