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SERVICE AND MAINTENANCE
PROCEDURES
Untrained personnel can perform basic maintenance func-
tions such as cleaning and replacing air filters. All other opera-
tions must be performed by trained service personnel. A quali-
fied service person should inspect the furnace once a year.
WARNING
!
FIRE, INJURY OR DEATH HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
The ability to properly perform maintenance on this
equipment requires certain knowledge, mechanical
skills, tools, and equipment. If you do not possess
these, do not attempt to perform any service and
maintenance on this equipment other than those
procedures recommended in the Owner's Manual.
CAUTION
!
ENVIRONMENTAL HAZARD
Failure to
follow
this
environmental pollution.
Remove and recycle all components or materials (i.e.
oil, refrigerant, control board, etc.) before unit final
disposal.
WARNING
!
ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD
Failure to follow this warning could result in personal
injury or death, or property damage.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF
position and install a lockout tag. There may be more
than one disconnect switch. Lock out and tag switch
with a suitable warning label. Verify proper operation
after servicing.
CAUTION
!
ELECTRICAL OPERATION HAZARD
Failure to follow this caution may result in improper
furnace operation or failure of furnace.
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation.
General
These instructions are written as if the furnace is installed in
an upflow application. An upflow furnace application is
where the blower is located below the combustion and
controls section of the furnace, and conditioned air is
discharged upward. Since this furnace can be installed in
any of the 4 positions shown in Figure 6, you must revise
your orientation to component location accordingly.
Electrical Controls and Wiring
Pressure Switches
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
440 04 6001 00
caution
may
result in
Specifications subject to change without notice.
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 Figure 7 for field wiring
information and to Figure 16 for furnace wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control will flash 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 Figure 2.) 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 display status
code 24 when fuse needs to be replaced.
Troubleshooting
Refer to the service label. (See Figure 5—Service Label.)
The Troubleshooting Guide (See Figure 15) 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.
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 Figure 5, and the troubleshooting
guide which can be obtained from your distributor.
Retrieving Stored Fault Codes
NOTE:
Fault codes cannot be retrieved if a thermostat
signal (24-v on W, Y, G, etc.) is present, or if any delays
such as blower off-delays are active.
The stored status codes will NOT be erased from the control
memory when 115- or 24-v power is interrupted. See the
Service Label (Figure 5) for more information. The most
recent fault code may be retrieved as follows:
1. Leave 115-v power connected to furnace.
2. Observe the status LED through the blower door (the
lower door on upflow applications) indicator. Refer to
the Service Label (Figure 5) to interpret the LED.
3. Remove the Main/Control door (the upper door on
upflow installations).
4. BRIEFLY (2−3 seconds) disconnect and reconnect
ONE of the main limit wires.
13
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