Code 24 Secondary Voltage Fuse Is Open; Fault Code 24-Secondary Voltage Fuse Is Open - Carrier 58MVP Troubleshooting Manual

Table 2—Air Conditioning (A/C) Airflow Setup Switch Position
AIR CONDITIONER AIRFLOW
(TONS) (CFM)
1200 or
Default
2000
1-1/2 600
2 800
2-1/2 1000
3 1200
3-1/2 1400
4 1600
5 2000
X—Indicates allowable selection.
CONTINUOUS FAN
(CFM)
Default
600
800
1000
1200
1400
1600
2000
* Add 15% additional CFM when Bypass Humidifier switch SW-3 on control board is used.
X—Indicates allowable selection.
OUTDOOR UNIT CAPACITY
A/C Setting
CF Setting
Fault Code 24
SECONDARY VOLTAGE FUSE IS OPEN—Indicates fuse is open and there is a short in low-voltage wiring.
STEP
1. Turn power off and remove blower access panel.
2. Is secondary voltage fuse blown? Check continuity to make sure.
3. Replace furnace control board.
4. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
Disconnect all thermostat leads from furnace control board (including HUM terminal) and replace
5.
secondary voltage fuse.
6. Depress door switch. Use a piece of tape to hold switch closed.
7. Does Fault Code 24 flash?
You have a short circuit in limit switch circuit. This includes limit switch, flame rollout switch, and
8.
auxiliary limit switch.
9. Fix problem and replace secondary voltage fuse if necessary.
10. Jumper R and W/W1 thermostat terminals on furnace control board.
11. Does Fault Code 24 occur when W/W1 is energized?
Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage
12.
fuse.
Disconnect PL2 from furnace control board and jumper R and W/W1 thermostat terminals on fur-
13.
nace control board.
14. Does Fault Code 24 occur when W/W1 is energized?
15. You have a short circuit in pressure switch circuit.
16. Does Fault Code 24 occur when low-pressure switch is energized?
17. Disconnect PL2 from furnace control board.
A/C SWITCH POSITION
A/C-1 A/C-2 A/C-3
OFF OFF OFF
ON OFF OFF
OFF ON OFF
ON ON OFF
OFF OFF ON
ON OFF ON
OFF ON ON
ON ON ON
Table 3—Continuous Fan (CF) Airflow Setup Switch Position
CF SWITCH POSITION
CF-1 CF-2 CF-3
OFF OFF OFF
ON OFF OFF
OFF ON OFF
ON ON OFF
OFF OFF ON
ON OFF ON
OFF ON ON
ON ON ON
Table 4—Two-Speed AC/HP Airflow Requirements (CFM)
036
3 Tons—1200
800
ACTION
ALLOWABLE FURNACE MODEL SETUP
040 060 080
3 Tons 3 Tons 3 Tons
1200 CFM 1200 CFM 1200 CFM
X X X
X X X
X X X
X X X
X X X
— — —
— — —
ALLOWABLE FURNACE MODEL SETUP
040 060 080
565* 515* 690*
X X
X X
X X
X X
X X
— — —
— — —
048
4 Tons—1600
1000
19
080 100
5 Tons 5 Tons
2000 CFM 2000 CFM
— —
X X
X X
X X
X X
X X
X X
080
100
(5 Ton)
690* 860*
X — —
X X X
X X X
X X X
X X X
X X
X X
060
5 Tons—2000
1000
YES NO
— —
5 3
— —
— —
— —
— —
8 10
— —
— —
— —
12 16
— —
— —
3 15
— —
17 20
— —
120
5 Tons
2000 CFM
—
X
X
X
X
X
X
120
1035*
—
X
X
X
X
X
X
GO TO
2
—
4
INDEX
6
7
—
9
4
11
—
13
14
—
9
—
18