Carrier furnace error codes

50 codes with causes and test steps, plus 4 settings tables.

Code	Meaning	Severity
10.1	L1 polarity fault	High
11	No previous code	Low
12	Blower on after power-up (normal)	Low
12.1	W (heat call) on at power up	Low
13	Limit circuit lockout	Critical
13.1	Limit lockout - main limit open over 3 minutes	High
14	Ignition lockout	Critical
14.1	Ignition lockout after 4 tries	High
14.2	Lockout - flame lost 3 times after 70 s of heating	High
14.3	Lockout - 7 flame-loss events in one heat call	High
15	Blower motor lockout	High
21	Gas heating lockout	Critical
21.1	24 VAC on gas valve when it should be off	Critical
22	Abnormal flame-proving signal	Critical
22.1	False flame	Critical
23	Pressure switch did not open	Medium
23.1	Main pressure switch stuck closed	Medium
23.2	Secondary pressure switch stuck closed	Medium
24	Secondary (24 V) fuse open	Medium
24.1	Fuse fault (24 V)	High
25	Invalid model selection or setup error	Medium
25.1	No program in control	High
25.2	Corrupted program file	High
25.3	Twinned furnaces not identical	Medium
25.4	Main program invalid, running on backup	Low
25.5	Installer settings corrupted	Low
25.6	Wrong program for this control	High
25.7	Non-condensing program in condensing furnace	High
27.1	Super plug program missing or corrupted	Medium
27.2	Super plug program missing or corrupted	Medium
27.3	Super plug program missing or corrupted	Medium
31	High-heat pressure switch or relay did not close or reopened	High
31.2	Secondary pressure switch (HPS) open	High
31.3	Secondary pressure switch lockout	High
32	Low-heat pressure switch did not close or reopened	High
32.1	Main pressure switch (LPS) open	High
33	Limit circuit fault	High
33.1	Main limit circuit switch open	High
34	Ignition proving failure	High
34.1	Ignition fault during ignition trials	High
34.2	Flame lost before blower on-delay	Medium
34.3	Flame lost after blower on-delay	High
43	Low-heat pressure switch open while high-heat switch closed	High
45	Control circuitry lockout	High
45.1	Control failure - flame circuit / memory / sequence	High
45.2	Control failure - gas valve relay will not close	High
45.3	Control failure - EEPROM memory	High
46.1	Momentary loss of power	Low
LED OFF	No amber LED - no power to control	High
Rapid Flash	Reversed 115-V polarity (or twinning phasing)	High

Settings and specs

Filter sizes by casing width and filter cabinet

Filters · 59SC6A

Location	Size	Side return filter	Bottom return filter	Type
Furnace casing	14-3/16 in. wide	16 x 25 x 3/4 in.	14 x 25 x 3/4 in.	Washable
Furnace casing	17-1/2 in. wide	(1) 16 x 25 x 3/4 in.	(1) 16 x 25 x 3/4 in.	Washable
Furnace casing	21 in. wide	(1) 16 x 25 x 3/4 in.	(1) 20 x 25 x 3/4 in.	Washable
Furnace casing	24-1/2 in. wide	(1) 16 x 25 x 3/4 in.	(1) 24 x 25 x 3/4 in.	Washable
Filter cabinet	16 in. high	(1) 16 x 25 x 3/4 in. or (1) 16 x 25 x 4-5/16 in.	-	Washable or media
Filter cabinet	20 in. high	(1) 20 x 25 x 3/4 in. or (1) 20 x 25 x 4-5/16 in.	-	Washable or media
Filter cabinet	24 in. high	(1) 24 x 25 x 3/4 in. or (1) 24 x 25 x 4-5/16 in.	-	Washable or media

Side-return filters can differ in size - measure the existing filter.
Every return-air inlet needs a filter.
Airflow over 1800 CFM needs at least a 20 x 25 in. filter.

Source: Carrier 59SC6A Installation, Start-up, Operating and Service and Maintenance Instructions (59SC6A-01SI), Table 9 Air Filter Selection and Duct Sizing, p.24 (printed p.21)

Filter sizes by casing width and filter cabinet

Filters · 59TP6A

Location	Size	Side return filter	Bottom return filter	Type
Furnace casing	14-3/16 in. wide	16 x 25 x 3/4 in.	14 x 25 x 3/4 in.	Washable
Furnace casing	17-1/2 in. wide	16 x 25 x 3/4 in.	16 x 25 x 3/4 in.	Washable
Furnace casing	21 in. wide	16 x 25 x 3/4 in.	20 x 25 x 3/4 in.	Washable
Furnace casing	24-1/2 in. wide	16 x 25 x 3/4 in.	24 x 25 x 3/4 in.	Washable
Filter cabinet	16 in. high	(1) 16 x 25 x 3/4 in. or (1) 16 x 25 x 4-5/16 in.	-	Washable or media
Filter cabinet	20 in. high	(1) 20 x 25 x 3/4 in. or (1) 20 x 25 x 4-5/16 in.	-	Washable or media
Filter cabinet	24 in. high	(1) 24 x 25 x 3/4 in. or (1) 24 x 25 x 4-5/16 in.	-	Washable or media

No internal filter rack in this furnace - an external filter is required.
Side-return filters can differ in size - measure the existing filter.
Not every family has the 14-3/16 in. casing.

Source: Carrier 59TP6A Installation, Start-up, Operating and Service and Maintenance Instructions, Table 7 Air Filter Selection and Duct Sizing, p.23 (PDF p.26 of 96-page file)

Minimum clearances to combustibles

Clearances · 59TP6A

Position	Clearance
Rear	0 in. (0 mm)
Front (combustion air openings)	1 in. (25 mm)
Front, required for service	24 in. (610 mm) - check local code
All sides of supply plenum	1 in. (25 mm) - check local code
Sides	0 in. (0 mm)
Vent	0 in. (0 mm)
Top of furnace	1 in. (25 mm)

Keep 1 in. from combustibles to supply duct for 36 in. horizontally from the furnace.
Do not set on carpet or combustible tile; downflow on combustible floor needs the accessory floor base unless on a matching coil casing.

Source: Carrier 59TP6A Installation, Start-up, Operating and Service and Maintenance Instructions, Table 2 Minimum Clearances to Combustible Materials, p.6 (PDF p.9 of 96-page file)

Minimum clearances to combustibles

Clearances · 59SC6A

Position	Minimum clearance
Rear	0
Front (combustion air openings in furnace and in structure)	1 in. (25 mm)
Required for service	24 in. (610 mm) (see note)
All sides of supply plenum	1 in. (25 mm) (see note)
Sides	0
Vent	0
Top of furnace	1 in. (25 mm)

Service and supply-plenum values are marked 'consult local building codes'.
Keep 1 in. (25 mm) from combustibles to supply ductwork for 36 in. (914 mm) horizontally from the furnace.
Downflow on a combustible or wood floor needs the special base unless installed on a factory cased coil or coil casing.
Same values for all sizes.

Source: Carrier 59SC6A Installation, Start-up, Operating and Service and Maintenance Instructions (59SC6A-01SI), Table 2 Minimum Clearances to Combustible Materials for All Units, p.8 (printed p.5)

Models covered

58SB0A045E14--1258SB0A045E17--1258SB0A070E14--1258SB0A070E17--1258SB0A070E17--1658SB0A070E21--1658SB0A090E17--1458SB0A090E21--1658SB0A090E21--2058SB0A090E24--2058SB0A110E21--2058SB0A110E24--2058SB0A135E24--2058SB0A155E24--2059MN7C060C17--1459MN7C060C21--2059MN7C080C17--1459MN7C080C21--2059MN7C100C21--2259MN7C120C24--2259SC5B026E14--1059SC5B040E14--1059SC5B040E17--1259SC5B060E14--1259SC5B060E17--1459SC5B080E17--1659SC5B080E21--2059SC5B100E21--2059SC5B100E21--2259SC5B120E24--2259SC5B140E24--2259SC6A026M14--1059SC6A040M14--1059SC6A040M17--1259SC6A060M14--1259SC6A060M17--1659SC6A080M17--1659SC6A080M21--2059SC6A100M21--2059SC6A100M21--2259SC6A120M24--2259SC6A140M24--2259TP6A040-1059TP6A040-1259TP6A060-1259TP6A060-1459TP6A080-1659TP6A080-2059TP6A100-2059TP6A120-22926TB30040V14926TB36040V17926TB36060V14926TB42060V17926TB48080V17926TB60080V21926TB60100V21926TB66100V21926TB66120V24PG96VTA30040APG96VTA36040BPG96VTA36060APG96VTA48060BPG96VTA48080BPG96VTA60080CPG96VTA60100CPG96VTA66120D

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.