035-14370-000 650.75-N4U
Unitary Products Group 37
9. Clean - vacuum all burners.
10. Replace all components in reverse order. Reconnect all
wirin
.
11. Restore electrical power and
as supply to the furnace.
12. Check furnace operation.
Cleaning the Secondary Heat Exchanger
1. Follow steps 1 thru 10 under Cleanin
the Primary Heat
Exchan
er.
2. Remove the vent pipin
from the venter housin
. 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
ently
removed from the secondary heat exchan
er.
3. With a stiff wire brush, brush out loose scale or soot.
4. Vacuum the secondary heat exchan
er.
5. Finish the cleanin
procedure by followin
steps 10 thru
12 under Cleanin
the Primary Heat Exchan
er.
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 on Page
11.
TROUBLESHOOTING
The following visual checks should be made before trouble-
shooting:
1. Check to see that the power to the furnace and the i
ni-
tion control module is ON.
2. The manual shutoff valves in the
as line to the furnace
must be open.
3. Make sure all wirin
connections are secure.
4. Review the sequence of operation.
Start the system by setting the thermostat above the room
temperature. Observe the system's response. Then use the
troubleshooting 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 indi-
cate 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 exam-
ple, six on flashes equals a number 6 fault code.
All flash code sequences are broken by a 2 second off period
.
CONTINUOUS FLASHING (1 sec on - 1 sec off):
This indi-
cates that flame was sensed when there was not a call for
heat. With this fault code the control will also turn on both the
inducer motor and supply air blower. This fault would typically
POWER SUPPLY POLARITY - 50A50-241 Control
Only
If the power supply polarity is reversed, the fol-
lowing unit operation will occur. On a call for heat, the
inducer will run, the HSI will glow and the gas valve will
energize and the burners will ignite. The burners will
immediately extinguish and the unit will recycle. This will
occur 3 times and then the unit will lockout. A “7” flash
code will be displayed. This code means the flame could
not be established. This occurs because the control can-
not sense flame with the power supply polarity reversed.
50A50-241 IGNITION CONTROL (P/N 031-01266-000)
Normal flame sense current is approximately
Low flame signal control lockout point is
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