Electrical Controls And Wiring; Troubleshooting; Component Test Sequence - Carrier 58MSA Service And Maintenance Instructions

10. Replace main furnace door.
Step 7—Electrical Controls and Wiring
There may be more than 1 electrical supply to the unit. Check
accessories and cooling unit for additional electrical supplies.
The electrical ground and polarity for 115-v wiring must be
maintained properly. Refer to Fig. 11 for field wiring information
and to Fig. 15 for unit wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control center will flash rapidly and prevent the furnace from
operating. The control system also requires an earth ground for
proper operation of the control center and flame sensing.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the control center. (See Fig. 12.) Any direct 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 fuse of
identical size.
With power to the unit disconnected, check all electrical connec-
tions for tightness. Tighten all screws on electrical connections. If
any smoky or burned connections are found, disassemble the
connection, clean all parts, strip wire, and reassemble properly and
securely.
Reconnect electrical supply to unit and observe unit through 1
complete operating cycle. Electrical controls are difficult to check
without proper instrumentation; if there are any discrepancies in
the operating cycle, contact your dealer and request service.
Step 8—Troubleshooting
For an explanation of fault codes, refer to service label located on
back of main furnace door or Fig. 16, and the Troubleshooting
Guide.
The control center stores 1 fault code (the last fault to occur) for a
period of 48 hrs or until the 115- or 24-v power is interrupted.
THREE-WIRE
BLK BLK
WHT WHT
GND
AUXILIARY
115-V
J-BOX
FIELD-SUPPLIED
DISCONNECT
NOTE 2
W C
FIVE
WIRE
HEATING-
ONLY
W
R
GND
G
C
NOTE 1
CONTROL
Y
BOX
24-V
TERMINAL
BLOCK
NOTES:
FURNACE
Fig. 11—Field Wiring
NOTE: Removing blower access panel will open blower access
panel door switch and terminate 115-v power to control center, and
fault code will be erased. Look into blower access panel sight glass
for current LED status.
The unit's component test is a useful troubleshooting tool since it
displays the current status (fault code) of the furnace and func-
tionally operates all furnace components except the gas valve. The
component test and methods to initiate it are described below.

COMPONENT TEST SEQUENCE

NOTE: All components are functionally operated except the gas
valve.
When component test is initiated, the following sequence of events
occurs:
1. LED flashes a fault code 4 times.
2. Inducer motor starts and continues to run for remainder of
component test.
3. Hot surface ignitor is energized for 15 sec, then de-energized.
4. Main blower operates at cooling speed for 10 sec, then turns
off.
5. Main blower operates at heating speed for 10 sec, then turns
off.
6. Inducer motor stops.
Component test can be initiated by one of the following proce-
dures.
INITIATING COMPONENT TEST AND RETRIEVING STA-
TUS CODE BY REMOVING MAIN LIMIT SWITCH WIRE
NOTE: NO thermostat signal may be present at control center
and all blower time delay off periods must be completed.
1. Leave 115-v power to furnace turned on.
2. Remove main furnace door.
3. Look into blower access panel sight glass for current LED
status.
NOTE: Leave blower access panel installed to maintain power to
control center to view current LED status.
FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-V WIRING
THERMOSTAT
R G Y
TERMINALS
CONDENSING
UNIT
TWO
WIRE
1. Connect Y-terminal as shown for proper operation.
2. Some thermostats require a "C" terminal connection as shown.
3. If any of the original wire, as supplied, must be replaced, use
same type or equivalent wire.
8
FIELD-SUPPLIED
DISCONNECT
208/230- OR
460-V
THREE
PHASE
208/230-V
SINGLE
PHASE
GND
A98209