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you must revise your orientation to component location
accordingly.
Electrical Controls and Wiring
Each pressure switch is labeled with the reference location (noted
as "COLLECTOR BOX- -LPS" or "HOUSING- -HPS" on the
switch). The nominal break point of each switch is shown on the
label below the reference location in inches of water column,
"W.C." The maximum and minimum break point of the switch is
+/- - 0.05 inches of water column from the nominal break point of
the switch. The maximum make point of the switch is 0.10 inches
of water above the maximum break point of the switch.
Example: Nominal break point on pressure switch is 0.68- -in.
W.C. The minimum break point of the switch is 0.63- -in. W.C.
The maximum break point of the switch is 0.73- -in. W.C. The
maximum make point of the switch is 0.83- -in. W.C.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
There may be more than one electrical supply to the furnace.
Check accessories and cooling unit for additional electrical
supplies that must be shut off during furnace servicing. Lock
out and tag switch with a suitable warning label.
The electrical ground and polarity for 115- -v wiring must be
properly maintained. Refer to Fig. 37 for field wiring information
and to Fig. 72 for furnace wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control will flashes rapidly and prevent the furnace from heating.
The control system also requires an earth ground for proper
operation of the control and flame- -sensing electrode.
The 24- -v circuit contains an automotive- -type, 3- -amp. fuse located
on the control. See Fig. 38. Any shorts of the 24- -v wiring during
installation, service, or maintenance will cause this fuse to blow. If
fuse replacement is required, use ONLY a 3- -amp. fuse. The control
LED will status code 24 when fuse needs to be replaced.
Troubleshooting
Refer to the service label. See Fig. 64.
The Troubleshooting Guide can be a useful tool in isolating
furnace operation problems. Beginning with the word "Start,"
answer each question and follow the appropriate arrow to the next
item. See Fig. 71.
The Guide will help to identify the problem or failed component.
After replacing any component, verify correct operation sequence.
Proper instrumentation is required to service electrical controls.
The control in this furnace is equipped with a Status Code LED
(Light- -Emitting Diode) to aid in installation, servicing, and
troubleshooting. Status codes can be viewed at the indicator in
blower door.
The amber furnace control LED is either ON
continuously, rapid flashing, or a code composed of 2 digits. The
first digit is the number of short flashes, the second digit is the
number of long flashes.
For an explanation of status codes, refer to service label located on
control door or Fig. 64, and the troubleshooting guide which can
be obtained from your distributor.
Retrieving Stored Fault Codes
The stored status codes will NOT be erased from the control
memory, when 115- - or 24- -v power is interrupted. The control will
store up to the last 7 Status Codes in order of occurrence.
1. To retrieve status codes, proceed with the following:
NOTE: NO thermostat signal may be present at control, and all
blower- -OFF delays must be completed.
a. Leave 115- -v power to furnace turned on.
b. Look into blower door indicator for current LED status.
c. Remove blower door.
NOTE: The Status Codes cannot be retrieved by disconnecting
the limit switch. To retrieve Status Codes, follow the procedure
below.
2. Turn Setup Switch, SW1- -1 "ON."
3. Manually close blower door switch.
4. Control will flash up to 7 Status Codes.
5. The last Status Code, or 8th Code, will be Code 11.
6. Turn SW1- -1 "OFF."
7. A continuously- -lit Amber LED will appear and indicates
proper operation.
8. Release blower door switch, install blower door and refer
to the SERVICE label on the control door for more infor-
mation.
Component Self- - Test
Component Test can ONLY be initiated by performing the
following:
1. Remove blower door.
2. Remove the wire from the "R" terminal of the control
board.
3. Turn Setup Switch, SW- -1- -6 "ON."
4. Manually close blower door switch.
Blower door switch opens 115- -v power to control. No component
operation can occur unless switch is closed. Caution must be taken
when manually closing this switch for service purposes.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury,
or death.
Blower door switch opens 115- -v power to furnace control.
No component operation can occur unless switch is closed.
Exercise caution to avoid electrical shock from exposed
electrical components when manually closing this switch for
service purposes.
5. Component Test sequence will function as follows:
a. The furnace control CPU turns the inducer motor ON at
high- -heat speed and keeps it ON through step c.
b. After waiting 10 sec the furnace control CPU turns the hot
surface igniter ON for 15 sec, then OFF.
c. The furnace control CPU then turns the blower motor
BLWM on at mid- -range airflow for 15 sec, then OFF.
d. After shutting the blower motor OFF the furnace control
CPU switches the inducer to low- -heat speed for 10 sec,
then OFF.
NOTE: The EAC terminals are energized when the blower is
operating.
After the component test is completed, 1 or more status codes (11,
25, or 41) will flash. See Service Label on control door or
service/status code instruction for explanation of status codes. See
Fig. 64.
NOTE: To repeat component test, turn setup switch SW1- -6 OFF
then back ON.
e. Turn setup switch SW1- -6 off.
6. RELEASE BLOWER DOOR SWITCH, reattach wire to
"R" terminal on furnace control board and replace blower
door.
78
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