Fault code 24 – Carrier 58MVP User Manual
Page 19
Fault Code 24
SECONDARY VOLTAGE FUSE IS OPEN—Indicates fuse is open and there is a short in low-voltage wiring.
STEP
ACTION
YES
NO
GO TO
1.
Turn power off and remove blower access panel.
—
—
2
2.
Is secondary voltage fuse blown? Check continuity to make sure.
5
3
—
3.
Replace furnace control board.
—
—
4
4.
Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
—
—
INDEX
5.
Disconnect all thermostat leads from furnace control board (including HUM terminal) and replace
secondary voltage fuse.
—
—
6
6.
Depress door switch. Use a piece of tape to hold switch closed.
—
—
7
7.
Does Fault Code 24 flash?
8
10
—
8.
You have a short circuit in limit switch circuit. This includes limit switch, flame rollout switch, and
auxiliary limit switch.
—
—
9
9.
Fix problem and replace secondary voltage fuse if necessary.
—
—
4
10.
Jumper R and W/W1 thermostat terminals on furnace control board.
—
—
11
11.
Does Fault Code 24 occur when W/W1 is energized?
12
16
—
12.
Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage
fuse.
—
—
13
13.
Disconnect PL2 from furnace control board and jumper R and W/W1 thermostat terminals on fur-
nace control board.
—
—
14
14.
Does Fault Code 24 occur when W/W1 is energized?
3
15
—
15.
You have a short circuit in pressure switch circuit.
—
—
9
16.
Does Fault Code 24 occur when low-pressure switch is energized?
17
20
—
17.
Disconnect PL2 from furnace control board.
—
—
18
Table 2—Air Conditioning (A/C) Airflow Setup Switch Position
AIR CONDITIONER
(TONS)
AIRFLOW
(CFM)
A/C SWITCH POSITION
ALLOWABLE FURNACE MODEL SETUP
A/C-1
A/C-2
A/C-3
040
060
080
080
100
120
Default
1200 or
2000
OFF
OFF
OFF
3 Tons
1200 CFM
3 Tons
1200 CFM
3 Tons
1200 CFM
5 Tons
2000 CFM
5 Tons
2000 CFM
5 Tons
2000 CFM
1-1/2
600
ON
OFF
OFF
X
X
X
—
—
—
2
800
OFF
ON
OFF
X
X
X
X
X
X
2-1/2
1000
ON
ON
OFF
X
X
X
X
X
X
3
1200
OFF
OFF
ON
X
X
X
X
X
X
3-1/2
1400
ON
OFF
ON
X
X
X
X
X
X
4
1600
OFF
ON
ON
—
—
—
X
X
X
5
2000
ON
ON
ON
—
—
—
X
X
X
X—Indicates allowable selection.
Table 3—Continuous Fan (CF) Airflow Setup Switch Position
CONTINUOUS FAN
(CFM)
CF SWITCH POSITION
ALLOWABLE FURNACE MODEL SETUP
CF-1
CF-2
CF-3
040
060
080
080
(5 Ton)
100
120
Default
OFF
OFF
OFF
565*
515*
690*
690*
860*
1035*
600
ON
OFF
OFF
X
X
X
—
—
—
800
OFF
ON
OFF
X
X
X
X
X
X
1000
ON
ON
OFF
X
X
X
X
X
X
1200
OFF
OFF
ON
X
X
X
X
X
X
1400
ON
OFF
ON
X
X
X
X
X
X
1600
OFF
ON
ON
—
—
—
X
X
X
2000
ON
ON
ON
—
—
—
X
X
X
* Add 15% additional CFM when Bypass Humidifier switch SW-3 on control board is used.
X—Indicates allowable selection.
Table 4—Two-Speed AC/HP Airflow Requirements (CFM)
OUTDOOR UNIT CAPACITY
036
048
060
A/C Setting
3 Tons—1200
4 Tons—1600
5 Tons—2000
CF Setting
800
1000
1000
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