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SERVICE
AND
MAINTENANCE
PROCEDURES
The
maxinmm
break
point
of the switch
is 0.73-in.
W.C. The
maximum
make point of the switch is 0.83-in.
W.C.
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.
ENVIRONMENTAL
HAZARD
Failure to follow this caution may result in environmental
pollution.
Remove and recycle all components or materials (i.e. oil,
refrigerant, control board, etc.) before unit final disposal.
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.
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 (except 140
model) shown in Fig. 2, 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 colunm,
"W.C." The maximum and nfinimum 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 nfinimum break point of the switch is 0.63-in. W.C.
ELECTRICALSHOCK
HAZARD
Failure to follow this warning could result in personal iniury
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 220-v wiring must be
properly maintained. Refer to Fig. 35 for field wiring information
and to Fig. 65 for furnace wiring information.
NOTE:
If the polarity is not correct, the STATUS LED on the
control will flash Code 10 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. 36. 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 be OFF when fuse needs to be replaced.
Troubleshooting
Refer to the service label. See Fig. 56.
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. 64.
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-Enfitting
Diode)
to aid in installation,
servicing,
and
troubleshooting.
Status codes can be viewed at the indicator in
blower door. The green furnace control LED is either ON, a
heartbeat (bright-dim)
continuously
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. 56, 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 220- or 24-v power is interrupted. See the Service
Label (Fig. 56) for more information. The most recent fault code
may be retrieved as follows:
1. Leave 220-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 (Fig. 56) to interpret the LED.
3. Remove the Main/Control door (the upper door on upflow
installations).
4. BRIEFLY disconnect and reconnect ONE of the main linfit
wires.
5. The LED will flash the last stored fault code. Refer to the
Service Label (Fig. 56) to interpret the LED.
6. A component test sequence will follow.
7. Reinstall the Main/Control door.
65
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