Carrier Heat Pump Error Codes

Updated October 13, 2026 · by Aurora Star Tech Inc.

44 Carrier Heat Pump error codes and diagnostic codes, with causes and troubleshooting steps for each. Select a code, or find your model below.

Homeowner with a heat pump problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Carrier Heat Pump error codes list

Code	Meaning	Severity
16	Lost communication with user interface	Medium
25	Invalid model plug / inverter size	High
31	High pressure switch open	High
32	Low pressure trip	Medium
33	Lost inverter communication	Medium
45	Outdoor control board failure	High
46	Brownout	Medium
47	No 230 V at unit	High
48	Lost inverter communication - lockout	High
49	Compressor over current	Medium
53	Outdoor air temperature sensor fault	Medium
54	Suction temperature sensor fault	Medium
55	Outdoor coil temperature sensor fault	Medium
56	OAT / coil thermistor out of range	Medium
57	Suction pressure transducer fault	Medium
59	Discharge temperature high (event)	Medium
61	Fan inverter fault	Medium
63	Fan inverter current fault	Medium
65	DC bus voltage low - speed limiting	Medium
66	Outdoor fan dropped out	Medium
67	Stator heater fault	Medium
68	10-minute stage 2 warm-up delay	Low
69	Inverter / compressor internal fault	High
71	Compressor dropped out	Medium
72	Suction over temperature (event)	Medium
73	Contactor shorted	High
74	Discharge temperature lockout	High
75	Maximum power mode - temperature	Medium
76	Fan inverter lockout	High
77	Maximum power mode - compressor current	Medium
79	Compressor / inverter fault (failed start)	Medium
81	Low stage thermal lockout	High
82	Suction over temperature lockout	High
83	Low pressure lockout (4 hours)	High
84	High pressure lockout (4 hours)	High
86	Fan inverter current lockout	High
88	Compressor / inverter lockout	High
91	Inverter DC over voltage (event)	Medium
92	Inverter DC under voltage (event)	Medium
95	Compressor over current lockout	High
96	DC under voltage lockout	High
97	DC over voltage lockout	High
98	High torque event	Medium
99	High torque lockout	High

Find codes by Carrier model

Carrier 2-stage 24ANB/25HNB

25HNB624 25HNB636 25HNB648 25HNB660 25HNB924 25HNB936 25HNB948 25HNB960

Carrier Infinity 18VS 25VNA8

25VNA813 25VNA824 25VNA825 25VNA836 25VNA837 25VNA848 25VNA860

Heat Pump troubleshooting guides

Amber STATUS or green COMM light not on Carrier · Heat Pump
Delay before the compressor restarts Carrier · Heat Pump
Heat pump will not defrost - HK32EA defrost board Carrier · Heat Pump
Noisy compressor or loud defrost shift - Carrier split systems Carrier · Heat Pump
Outdoor ECM fan not running - Carrier 25HNB9/24ANB1 Carrier · Heat Pump
Outdoor unit unresponsive after several faults Carrier · Heat Pump
Outdoor unit will not run - HK32EA defrost board heat pumps Carrier · Heat Pump

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.