Carrier 58MVP Troubleshooting Manual page 13

STEP
Connect a DC voltmeter across ORANGE (+) and VIOLET (-) wires at connec-
tor PL13, then repeat the COMPONENT TEST by turning setup switch SW-6
17.
OFF and then back ON. Do you see approximately the same DC voltages
across ORANGE and VIOLET wires that you saw in Step 15?
18. Replace blower motor.
You have an open wire or bad terminal on either the ORANGE or VIOLET wire
19.
between connectors PL13 and PL3. Repair it or replace blower harness(es).
20. Remove tape from door switch and turn power off at main disconnect.
21. Does blower wheel rub against blower housing?
22. Does blower wheel turn freely?
23. Is blower wheel firmly mounted on motor shaft?
Replace blower motor. Inspect electronics portion of failed motor for water dam-
24.
age. If present, find source of water and fix. Check A-coil and/or humidifier.
25. Disconnect jumper wire across R and W/W1 thermostat terminals.
Turn power back on. Depress door switch. Use a piece of tape to hold switch
26.
closed. Wait a few sec for self test before proceeding to next step.
27. 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
28.
MTR2?
You have an open wire or bad terminal on either the BLACK or WHITE wire
29.
between furnace control board and blower motor MTR2.
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
30.
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, then repeat COM-
PONENT TEST by turning setup switch SW-6 OFF and then back ON. Does
31.
voltage 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)
Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13
then repeat COMPONENT TEST by turning setup switch SW-6 OFF and then
32.
back ON. Do you see approximately the same DC voltages across RED and
BLUE wires that you saw in Step 30?
You have an open wire or bad terminal on either the RED or BLUE wire be-
33.
tween connectors PL13 and PL3. Repair it or replace blower harness(es).
34. 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 (-), then put setup switch SW-6 for COM-
PONENT TEST in ON position. Does voltage across the RED and YELLOW
35. 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 then repeat COM-
PONENT TEST by turning setup switch SW-6 OFF and then back ON. Does
36. voltage across PL3-1 and PL3-4 change 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 then repeat COMPONENT TEST by turning setup switch SW-6 OFF and
37.
then back ON. Do you see approximately the same DC voltages across RED
and YELLOW wires that you saw in Step 35?
You have an open wire or bad terminal on either the RED or YELLOW wire be-
38.
tween connectors PL13 and PL3. Repair it or replace blower harness(es).
Go to page number indicated in Index for CLEANUP AND START-UP
INSTRUCTIONS. If problem persists on an intermittent basis, replace blower
39.
motor. If problem still persists on an intermittent basis after replacing blower
motor, contact your distributor.
Turn power off and remove blower access panel. Depress door switch. Use a
40. piece of tape to hold switch closed. Wait a few sec for self test before proceed-
ing to next step.
13
YES NO GO TO
18 19 —
— — 5
— — 5
— — 21
4 22 —
23 24 —
25 4 —
— — 5
— — 26
— — 27
28 4 —
30 29 —
— — 5
32 31 —
18 16 —
34 33 —
— — 5
— — 35
37 36 —
18 16 —
18 38 —
— — 5
— — INDEX
— — 41