Carrier 58MVP Troubleshooting Manual page 35

In an effort to provide a method of troubleshooting inducer and blower motor by themselves, the following procedure may save you some time
in the event any of the following fault codes are the reason for service call (12, 32, 41, 42, or 44). If you get any other fault code, you should
use main troubleshooting guide to isolate problem.
STEP
1. Turn power off, remove blower access panel, and disconnect R thermostat lead.
Turn power on and depress door switch. Use a piece of tape to hold switch
2.
closed.
3. Put setup switch SW-6 for COMPONENT TEST in ON position.
4. After COMPONENT TEST is completed, does Fault Code 11 flash?
Turn power off, put setup switch SW-6 for COMPONENT TEST in OFF position,
5.
and reconnect R thermostat lead to furnace control board.
Replace blower access panel and turn power on. Wait a few sec, then reset
6.
thermostat. Observe operation of furnace through 1 heating cycle.
7. Go to page number indicated in Index for START HERE section.
8. Does Fault Code 42 flash?
9. Does inducer motor MTR1 turn on and come up to speed?
10. Does inducer wheel rub against inducer housing?
11. Does inducer wheel turn freely?
12. Do you have 120v between I1 and I2 on furnace control board?
13. Do you have 120v between terminals PL7-6 and PL7-12?
You have an open wire or bad terminal on either the BLACK or WHITE wire
14.
between furnace control board and inducer motor MTR1.
Are all pins and wire leads intact on connectors between furnace control board
15.
and inducer motor?
16. Fix problem.
Go to page number indicated in Index for CLEANUP AND START-UP
17.
INSTRUCTIONS.
Check Inducer PW line. To do this, connect a DC voltmeter across terminals
PL7-2 BROWN (+) and PL7-10 YELLOW (-) on inducer motor. Repeat COM-
PONENT TEST by turning setup switch SW-6 OFF and then back ON. Does
18. voltage across PL7-2 and PL7-10 change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (2.0 — 3.0 vdc)
• State 3—HIGH (7.0 — 8.0 vdc)
Replace inducer motor or inducer motor assembly. Inspect electronics portion of
19. failed motor for water damage. If present, find source of water and fix. Check
A-coil and/or humidifier.
Disconnect PL7 from inducer motor and connect a DC voltmeter across termi-
nals PL7-2 BROWN (+) and PL7-10 YELLOW (-). Repeat COMPONENT TEST
by turning setup switch SW-6 OFF and then back ON. Does voltage across
20. PL7-2 and PL7-10 change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (6.0 — 7.0 vdc)
• State 3—HIGH (10.5 — 11.5 vdc)
Connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-4 YEL-
LOW (-) on furnace control board. Repeat COMPONENT TEST by turning
setup switch SW-6 OFF and then back ON. Does voltage across PL1-6 and
21. PL1-4 change between states as shown below?
• State 1—OFF (-0.1 — 0.1 vdc)
• State 2—LOW (6.0 — 7.0 vdc)
• State 3—HIGH (10.5 — 11.5 vdc)
22. Replace furnace control board.
You have an open wire or bad terminal on either the BROWN or YELLOW wire
23.
between connectors PL1 and PL7. Repair it or replace main harness.
Check RPM feedback line. To do this, connect a DC voltmeter across terminals
PL7-2 BROWN (+) and PL7-1 ORANGE (-) on inducer motor. Repeat COMPO-
NENT TEST by turning setup switch SW-6 OFF and then back ON. Does volt-
age across BROWN and ORANGE wires change between states as shown be-
24.
low?
• State 1—OFF (11.5 — 12.5 vdc)
• State 2—LOW (10.2 — 11.2 vdc)
• State 3—HIGH (8.4 — 9.4 vdc)
Appendix D
Quick Motor Test Procedure
35
YES NO GO TO
— — 2
— — 3
— — 4
5 8 —
— — 6
— — 7
— — INDEX
9 27 —
24 10 —
16 11 —
12 19 —
13 16 —
15 14 —
— — 16
18 16 —
— — 17
— — INDEX
19 20 —
— — 17
19 21 —
23 22 —
— — 17
— — 17
25 19 —