Carrier 58MCA - Troubleshooting

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
58MCA AND 58MXA FURNACES
For an explanation of fault codes, refer to service label located on
back of main furnace door or Fig 19, and the troubleshooting guide
Fig 20.
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.
NOTE: Removing blower access panel will open blower access
panel door switch and terminate 24-v power to control center, and
fault code will be erased. Look into blower access panel sight glass
for current LED status.
1. To retrieve fault code, proceed with the following:
NOTE: NO thermostat signal may be present at control center,
and all blower time delay off periods must be completed.
a. Leave 115-v power to furnace turned on.
b. Remove main furnace door.
c. Look into blower access panel sight glass for current LED
status.
d. Remove blower access panel.
NOTE: Leave blower access panel installed to maintain power to
control center to view current LED status.
e. BRIEFLY remove either wire from the main limit switch
until LED goes out, then reconnect it.
NOTE: If wire to main limit is disconnected longer than 4 sec,
main blower starts and retrieval request is ignored.
2. When above items have been completed, the following will
occur:
a. LED flashes a fault code 4 times. Record this fault code for
further troubleshooting.
b. Inducer motor operates for 10 sec, then turns off.
c. Hot surface ignitor is energized for 15 sec, then de-
energized.
d. Main blower operates at cooling speed for 10 sec, then
turns off.
e. Main blower operates at heating speed for 10 sec, then
turns off.
Items a. through e. above will assist in furnace troubleshooting
since all components are functionally operated except the gas
valve. This procedure is also referred to as "Component Test."
3. Operate furnace through 1 heat cycle to test for proper
operation and check LED status.
4. If furnace is operating properly and LED indicates proper
operation, replace main furnace door.
5. Component Test can also be initiated by performing the
following:
Fig. 10—Burner Flame
A89020
Fig. 11—Gasket on Collector Box
A93081
Fig. 12—Hot Surface Ignitor Location and Burner
Assembly
A93260
BURNER
IGNITOR
13
32
"
11
32
"
7
8
"
C
L
C
L
IGNITOR
ASSEMBLY
IGNITOR
ASSEMBLY
CELL
PANEL
BURNER
BURNER BOX
9