Carrier 58MVP Troubleshooting Manual page 36

STEP
Connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-5 OR-
ANGE (-) on furnace control board. Repeat COMPONENT TEST by turning
setup switch SW-6 OFF and then back ON. Does voltage across BROWN and
25. ORANGE wires change between states as shown below?
• State 1—OFF (11.5 — 12.5 vdc)
• State 2—LOW (10.2 — 11.2 vdc)
• State 3—HIGH (8.4 — 9.4 vdc)
You have an open wire or bad terminal on ORANGE wire between connectors
26.
PL1 and PL7. Repair it or replace main harness.
27. Does Fault Code 41 flash?
28. Does blower motor MTR2 turn on and come up to speed?
29. Remove tape from door switch and turn power off at main disconnect.
30. Does blower wheel rub against blower housing?
31. Does blower wheel turn freely?
32. Is blower wheel firmly mounted on motor shaft?
Replace blower motor. Inspect electronics portion of failed motor for water dam-
33.
age. If present, find source of water and fix. Check A-coil and/or humidifier.
34. Put setup switch SW-6 for COMPONENT TEST in OFF position.
Turn power on and depress door switch. Use a piece of tape to hold switch
35.
closed. Wait a few sec for self test before proceeding to next step.
36. Do you have 120v between B1 and B2 on furnace control board?
Do you have 120v between BLACK and WHITE power leads at blower motor
37.
MTR2?
You have an open wire or bad terminal on either the BLACK or WHITE wire
38. between furnace control board and blower motor MTR2. Repair it or replace
blower harness(es).
Check Blower ON/OFF line. To do this, connect a DC voltmeter across termi-
nals PL3-1 RED (+) and PL3-5 BLUE (-), then put setup switch SW-6 for COM-
PONENT TEST in ON position. Does voltage across RED and BLUE wires
39.
change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—ON (9.0 — 10.0 vdc)
Disconnect PL3 from furnace control board and connect a DC voltmeter across
terminals PL3-1 (+) and PL3-5 (-) on furnace control board. Repeat COMPO-
NENT TEST by turning setup switch SW-6 OFF and then back ON. Does volt-
40.
age across PL3-1 and PL3-5 change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—ON (11.0 — 12.0 vdc)
You have an open wire or bad terminal on either the RED or BLUE wire be-
41.
tween connectors PL13 and PL3. Repair it or replace blower harness(es).
Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13.
Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back
ON. Does voltage across RED and BLUE wires change between states as
42.
shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—ON (9.0 — 10.0 vdc)
43. Put setup switch SW-6 for COMPONENT TEST in OFF position.
Check Blower PW line. To do this, connect a DC voltmeter across terminals
PL3-1 RED (+) and PL3-4 YELLOW (-) on furnace control board, then put setup
switch SW-6 for COMPONENT TEST in ON position. Does voltage across RED
44. and YELLOW wires change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (2.5 — 3.0 vdc)
• State 3—HIGH (7.0 — 7.5 vdc)
Disconnect PL3 from furnace control board and connect a DC voltmeter across
terminals PL3-1 (+) and PL3-4 (-) on furnace control board. Repeat COMPO-
NENT TEST by turning setup switch SW-6 OFF and then back ON. Does volt-
45. age across PL3-1 and PL3-4 change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (3.0 — 4.0 vdc)
• State 3—HIGH (9.0 — 10.0 vdc)
Connect a DC voltmeter across RED (+) and YELLOW (-) wires at connector
PL13. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then
back ON. Does voltage across RED and YELLOW wires change between
46. states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (2.5 — 3.0 vdc)
• State 3—HIGH (7.0 — 7.5 vdc)
You have an open wire or bad terminal on either the RED or YELLOW wire be-
47.
tween connectors PL13 and PL3. Repair it or replace blower harness(es).
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