Carrier 58MVP User Manual

Page 38

30.

Does blower wheel rub against blower housing?

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31.

Does blower wheel turn freely?

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32.

Is blower wheel firmly mounted on motor shaft?

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33.

Replace blower motor or blower control module attached to the blower motor. If you replace the
blower control module go to step 51. Always inspect failed motor for water damage. If present, find
source of water and fix. Check A-coil and/or humidifier.

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34.

Put setup switch SW-6 for COMPONENT TEST in OFF position.

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35.

Turn power on and depress door switch. Use a piece of tape to hold switch closed. Wait a few sec
for self test before proceeding to next step.

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36.

Do you have 120v between B1 and B2 on furnace control board?

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37.

Do you have 120v between BLACK and WHITE power leads at blower motor MTR2?

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38.

You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace con-
trol board and blower motor MTR2. Repair it or replace blower harness(es).

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39.

Check Blower ON/OFF line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+)
and PL3-5 BLUE (-), then put setup switch SW-6 for COMPONENT TEST in ON position. Does
voltage across RED and BLUE wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—ON (9.0 — 10.0 vdc)

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40.

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+)
and PL3-5 (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6
OFF and then back ON. Does 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)

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41.

You have an open wire or bad terminal on either the RED or BLUE wire between connectors PL13
and PL3. Repair it or replace blower harness(es).

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42.

Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13. Repeat COMPO-
NENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across RED and
BLUE wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—ON (9.0 — 10.0 vdc)

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43.

Put setup switch SW-6 for COMPONENT TEST in OFF position.

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44.

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 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)

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45.

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+)
and PL3-4 (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6
OFF and then back ON. Does voltage 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)

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46.

Connect a DC voltmeter across RED (+) and YELLOW (-) wires at connector PL13. Repeat COM-
PONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across RED
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)

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47.

You have an open wire or bad terminal on either the RED or YELLOW wire between connectors
PL13 and PL3. Repair it or replace blower harness(es).

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48.

Check RPM feedback line. To do this, connect a DC voltmeter across terminals PL3-2 ORANGE (+)
and PL3-3 VIOLET (-). Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then
back ON. Does voltage across ORANGE and VIOLET wires change between states as shown be-
low?

• State 1—OFF (12.0 — 12.5 vdc)
• State 2—LOW (10.7 — 11.7 vdc)
• State 3—HIGH (9.7 — 10.7 vdc)

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49.

Connect a DC voltmeter across ORANGE (+) and VIOLET (-) wires at connector PL13. Repeat
COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across
ORANGE and VIOLET wires change between states as shown below?

• State 1—OFF (12.0 — 12.5 vdc)
• State 2—LOW (10.7 — 11.7 vdc)
• State 3—HIGH (9.7 — 10.7 vdc)

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50.

You have an open wire or bad terminal on either the ORANGE or VIOLET wire between connectors
PL13 and PL3. Repair it or replace blower harness(es).

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