SERVICE AND MAINTENANCE PROCEDURES
FIRE, INJURY, OR DEATH HAZARD
Failure to follow this warning could result in possible damage
to this equipment, serious personal injury, or death.
The ability to properly perform maintenance on this equip-
ment requires certain knowledge, mechanical skills, tools, and
equipment. If you do not possess these, do not attempt to
perform any maintenance on this equipment other than those
procedures recommended in the User’s Manual.
ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD
Failure to follow this warning could result in personal injury
or death, or property damage.
Before servicing, disconnect all electrical power to furnace.
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 con-
trols. Wiring errors can cause improper and dangerous
operation.
Step 1—Introduction
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 Fig. 4,
you must revise your orientation to component location accord-
ingly.
ELECTRICAL CONTROLS AND WIRING
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.
The electrical ground and polarity for 115-v wiring must be
properly maintained. Refer to Fig. 25 for field wiring information
and to Fig. 56 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 Fig. 24.) 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.
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. It can be viewed through the sight glass in blower
access door. The 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
blower access door or Fig. 55 and the troubleshooting guide which
can be obtained from your distributor.
See Fig. 60, a brief Troubleshooting Guide.
For Controls With an Amber LED
The stored status code will not be erased from the control memory,
if 115- or 24-v power is interrupted.
1. To retrieve status code, 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. Remove outer access door.
c. Look into blower access door sight glass for current LED
status. Removing blower access door will open blower
access door switch and terminate 115-v power to control so
that status code is not displayed.
Table 11—Orifice Size* And Manifold Pressure For Gas Input Rate (Continued)
(Tabulated Data Based On 22,000 Btuh Per Burner, Derated 4 Percent For Each 1000 Ft Above Sea Level)
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58
0.60
0.62
0.64
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A.
Only
9001
to
10,000
600
43
2.7
43
2.8
43
2.9
43
3.0
625
43
2.5
43
2.6
43
2.6
43
2.7
650
43
2.3
43
2.4
43
2.4
43
2.5
675
43
2.1
43
2.2
43
2.3
43
2.3
700
48
3.7
43
2.0
43
2.1
43
2.2
725
48
3.5
48
3.6
48
3.7
43
2.0
* Orifice numbers 43 are factory installed
40
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