Burner Removal/Cleaning
The main burners should be checked periodically for dirt
accumulation.
If cleaning is required, follow this procedure:
1. Turn off the electrical power to the unit.
2. Turn off the gas supply at the external manual shutoff valve
and loosen the ground union joint.
3. Remove the upper access panel and remove the burner
box cover.
4. Remove the screws that hold the burner box assembly to
the vest panel and remove the assembly.
5. Remove burners from the burner assembly.
6. Burners may be cleaned by rinsing in hot water.
7. Reassemble the burners in the reverse order.
Cleaning the Heat Exchanger
1. Turn off the main manual gas valve external to the furnace.
2. Turn off electrical power to the furnace.
3. Remove the upper access panel and remove the burner
box cover.
4. Disconnect wires from flame sensor, rollout switch and HSI
igniter. Remove igniter carefully, as it is easily broken.
CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper
and dangerous operation. Verify proper operation af-
ter servicing.
5. Remove the screws that hold the burner box assembly to
the vestibule panel and remove the assembly. The upper
portion of the heat exchanger will now be exposed.
6. Remove the upper cover plate at the top of the furnace.
Remove the internal baffle.
7. The upper portion of the heat exchanger is now exposed.
8. With a long flexible wire brush, clean inside each tube at
both the top and bottom. The brush must pass around the
rear heat exchanger tubes. Vacuum loose scale and dirt
from each tube.
9. Clean - vacuum all burners.
10. Replace all components in reverse order. Reconnect all
wiring.
11. Restore electrical power and gas supply to the furnace.
12. Check furnace operation.
Cleaning the Secondary Heat Exchanger
1. Follow steps 1 thru 10 under "Cleaning the Primary Heat
Exchanger."
2. Remove the vent piping from the venter housing. Discon-
nect the drain lines from the venter and from the conden-
sate drain pan. Remove the venter blower and the
condensate pan. The turbulators can then be gently re-
moved from the secondary heat exchanger.
3. With a stiff wire brush, brush out loose scale or soot.
4. Vacuum the secondary heat exchanger.
5. Finish the cleaning procedure by following steps 10 thru
12 under "Cleaning the Primary Heat Exchanger."
VENT/AIR INTAKE
Should it be necessary to service the vent/air intake system,
the manufacturer recommends this service be conducted by a
qualified service agency.
The operation of this appliance requires the reassembly and
resealing of the vent/air intake system as specified onPage 11.
TROUBLESHOOTING
The following visual checks should be made before trou-
bleshooting:
1. Check to see that the power to the furnace and the ignition
control module 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.
Start the system by setting the thermostat above the room tem-
perature. Observe the system’s response. Then use the trou-
bleshooting section in this manual to check the system’s operation.
FURNACE CONTROL DIAGNOSTICS
The furnace has built-in, self diagnostic capability. If a system
problem occurs, a fault code is shown by a blinking LED. It is
located behind a clear view port in the blower compartment
door. DO NOT remove the furnace blower compartment panel
OR turn off furnace power as either action will clear the control’s
memory of the fault.
The control continuously monitors its own operation and the
operation of the system. If a failure occurs, the LED will indicate
the failure code. If the failure is internal to the control, the light
will stay on continuously. In this case, the entire control should
be replaced as the control is not field repairable.
If the sensed failure is in the system (external to the control),
the LED will flash in the following flash-pause sequences to
indicate failure status.
Flash sequence codes 2 thru 9 are as follows. LED will turn "on"
for 1/4 second and "off" for 1/4 second. This pattern will be
repeated the number of times equal to the code. For example,
six "on" flashes equals a number 6 fault code.
650.75-N4U
26
Unitary Products Group
