# 47860A005
Page 25
Main Burners
Light the burners and allow to operate for a few minutes to
establish normal burning conditions. Observe the main
burner flames. Compare this observation to Figure 34 to
determine if proper flame adjustment is present. Flame
should be predominantly blue in color and strong in appear-
ance. Check that all burners are lit, and that the flame does
not impinge on the sides of the heat exchanger.
Distorted flame or yellow tipping of the natural gas main
burner flame, or long yellow tips on propane, may be
caused by lint accumulation or dirt inside the burner or
burner ports, at the air inlet between the burner and
manifold pipe, or obstructions over the main burner orifice.
Use a soft brush or vacuum to clean the affected areas.
Typical Flame Appearance
(Main Burners)
Figure 34
Heat
Exchanger
Burner
Flame
(Blue Only)
Burner
Gas
Manifold
CONTROL SYSTEM DIAGNOSTICS
Troubleshooting
The following visual checks should be made before
troubleshooting:
1. Check to see that the power to the furnace and the
blower control board is on.
2. The manual shutoff valves in the gas line to the
furnace must be open.
3. Make sure all wiring connections are secure.
4. Review the
Sequence of Operation
(see page 22).
Start the system by setting the thermostat above the room
temperature. Observe the system’s response. Then use
the information provided in this section to check the
system’s operation.
The furnace has a built-in, self-diagnostic capability. If a
system problem occurs, a fault code is shown by an LED
on the control board. The control continuously monitors its
own operation and the operation of the system. If a failure
occurs, the LED will indicate the failure code. The flash
codes are presented in Table 5.
Fault Code History Button
The control stores the last five fault codes in memory. A
pushbutton switch is located on the control (see Figure 35
on page 27). When the pushbutton switch is pressed and
released, the control flashes the stored fault codes. The
most recent fault code is flashed first; the oldest fault code
is flashed last.
To clear the fault code history, press and hold pushbutton
switch in for more than 5 seconds before releasing.
Failure Codes
Table 5
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I
REPAIR PARTS
The following repair parts are available from the local
distributor. When ordering parts, include the complete
furnace model number and serial number which are
printed on the rating plate located on the furnace.
Control Group
Transformer
High limit control
Auxiliary limit (if used)
