Carrier Heat Pump Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your Carrier heat pump? This guide explains what the most common Carrier heat pump error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed HVAC technicians for Carrier heat pump repair across Metro Vancouver and the Fraser Valley.

The codes below apply across common Carrier models (Infinity, Performance, Comfort). Meanings follow Carrier’s documented fault codes — always confirm against your unit’s own manual, because exact wording can vary by model, control board and firmware.

How to read Carrier heat pump error codes

Carrier ducted heat pumps use TWO different diagnostic systems depending on generation. (1) STANDARD 2-STAGE units (Infinity 25HNA/25HNB, Performance 25HPA, 24ANA, etc.): a single AMBER status light on the outdoor unit control board flashes a 2-digit code. Short flashes give the first digit, long flashes the second digit (e.g. 3 short + 2 long = code 32). On an Infinity touchscreen thermostat the same condition is shown as a numeric status code. (2) VARIABLE-SPEED GREENSPEED units (Infinity 24VNA/25VNA, 18VS): the Infinity touchscreen thermostat displays System Fault codes in an XX-YY format (e.g. 61-41), where XX identifies the fault and YY the severity/state. IMPORTANT: the 2-digit numbers do NOT mean the same thing across the two systems and across some model years, so a code must always be read against the matching model's service manual. Basic single-stage Comfort-series heat pumps have no on-board code display.

Carrier heat pump error codes & what they mean

These are the Carrier heat pump codes our Greater Vancouver technicians see most. Anything marked pro repair involves electrical, refrigerant, sensor or control-board work that must be done by a licensed HVAC technician — never open the indoor/outdoor unit or refrigerant lines yourself.

Code	What it usually means	Common causes	Safe to check yourself
16	Communication with the user interface / Infinity thermostat lost (2-stage Infinity/Performance flash-code system) pro repair	Damaged or loose ABCD communication wiring between outdoor unit, indoor unit and thermostat; Reversed or miswired communication terminals; Failed outdoor control board or thermostat	Confirm the thermostat screen is on and the breaker/disconnect is on; Restart the system once at the breaker; Confirm the thermostat is set to the intended Heat/Cool/Auto mode
25	Invalid model plug (the model-identifying plug on the outdoor control board is missing, wrong, or unreadable) pro repair	Model plug not installed after a board replacement; Wrong model plug fitted; Damaged model plug or board socket	Restart the system once at the breaker; This typically follows a service/board replacement — contact the installer
31	High-pressure switch open (refrigerant high-side pressure too high) pro repair	Dirty or blocked outdoor coil (cooling) or indoor coil/airflow restriction (heating); Dirty air filter or closed registers reducing airflow; Outdoor fan motor failure	Replace or clean a dirty air filter; Clear snow, ice, leaves and debris from around the outdoor unit; Make sure supply and return registers are open and unblocked
32	Low-pressure switch open (refrigerant low-side pressure too low; on some models combined with discharge-temperature switch) pro repair	Low refrigerant charge / refrigerant leak; Dirty indoor coil or dirty filter reducing airflow in heating; Iced-over outdoor coil in heating from a failed defrost	Replace or clean a dirty air filter; Clear snow, ice and debris from the outdoor unit; Restart the system once at the breaker
45	Outdoor unit control board fault / control fault pro repair	Failed outdoor control board; Power-supply problem to the board; Moisture or corrosion on the board	Restart the system once at the breaker/disconnect
46	Brown-out / low line voltage (incoming 230V supply too low) pro repair	Utility brown-out or sagging supply voltage; Undersized or loose wiring / corroded connections; Loose breaker or disconnect connections	Confirm the breaker and outdoor disconnect are fully on; Check whether other large appliances are dimming/struggling (possible utility issue); Restart the system once at the breaker
47	No 230V power present at the outdoor unit pro repair	Tripped breaker or pulled outdoor disconnect; Blown fuse; Loose or broken high-voltage wiring to the unit	Check the breaker and the outdoor disconnect are on; Reset a tripped breaker once; if it trips again, stop and call a technician; Restart the system once at the breaker
53	Outdoor air temperature (OAT) sensor fault pro repair	Failed outdoor air thermistor; Disconnected or damaged sensor wiring; Sensor out of resistance range	Restart the system once at the breaker
55	Outdoor coil temperature sensor fault (this sensor governs the defrost cycle on a heat pump) pro repair	Failed outdoor coil thermistor; Disconnected or damaged sensor wiring; Sensor knocked loose from the coil	Clear snow and ice from the outdoor coil; Restart the system once at the breaker
56	Thermistors (outdoor air and outdoor coil) out of range pro repair	One or both outdoor thermistors reading out of range; Wiring short or open at the sensors; Outdoor control board fault	Restart the system once at the breaker
71	Low-stage compressor thermal cutout (internal overload on the low-stage / first-stage compressor opened) pro repair	Compressor overheating from low airflow or dirty coils; Low or high refrigerant pressure; Failing compressor	Replace a dirty filter and clear debris/snow from the outdoor unit; Allow the unit time to cool down; Restart the system once at the breaker
72	High-stage compressor thermal cutout (internal overload on the high-stage / second-stage compressor opened) pro repair	Compressor overheating; Dirty coils or restricted airflow; Refrigerant charge or pressure problem	Replace a dirty filter and clear debris/snow from the outdoor unit; Allow the unit time to cool down; Restart the system once at the breaker
73	Contactor stuck/shorted closed (compressor contactor not opening when commanded off) pro repair	Welded or stuck compressor contactor; Control wiring fault	Turn the system off at the thermostat; if the outdoor unit keeps running, shut it off at the disconnect/breaker and call a technician
74	No 230V power at the compressor (25HNA9 / two-stage models) pro repair	Open compressor contactor; Failed contactor coil; Broken or loose compressor power wiring	Confirm the breaker and disconnect are on; Restart the system once at the breaker
81	Low-stage thermal lockout (low-stage thermal cutout tripped repeatedly, e.g. 3 times; unit locked out) pro repair	Persistent compressor overheating; Ongoing airflow restriction or dirty coils; Refrigerant charge/pressure problem	Replace a dirty filter and clear debris/snow from the outdoor unit; Restart the system once at the breaker; if it locks out again, call a technician
82	High-stage thermal lockout (high-stage thermal cutout tripped repeatedly, e.g. 3 times; unit locked out) pro repair	Persistent compressor overheating; Ongoing airflow restriction or dirty coils; Refrigerant charge/pressure problem	Replace a dirty filter and clear debris/snow from the outdoor unit; Restart the system once at the breaker; if it locks out again, call a technician
83	Low-pressure lockout (low-pressure switch tripped repeatedly, e.g. 3 times; unit locked out) pro repair	Refrigerant leak / low charge; Persistent airflow restriction; Iced outdoor coil from failed defrost	Replace a dirty filter and clear ice/snow/debris from the outdoor unit; Restart the system once at the breaker; if it locks out again, call a technician
84	High-pressure lockout (high-pressure switch tripped repeatedly, e.g. 3 times; unit locked out) pro repair	Dirty/blocked outdoor coil in cooling or indoor coil/airflow restriction in heating; Outdoor fan failure; Refrigerant overcharge	Replace a dirty filter and clear debris/snow from the outdoor unit; Make sure registers are open; Restart the system once at the breaker; if it locks out again, call a technician
41-13	Defrost timeout — the target outdoor-coil temperature was not reached during a defrost cycle (Greenspeed variable-speed System Fault code) pro repair	Outdoor coil heavily iced or coil temperature sensor (OCT) error; Low refrigerant charge; Reversing valve not fully shifting into defrost	Clear ice, snow and debris from the outdoor coil and around the unit; Let a normal defrost cycle complete before judging; Restart the system once at the breaker
51-01	Outdoor air temperature (OAT) thermistor open (resistance too high) pro repair	Open/failed outdoor air thermistor; Disconnected or damaged sensor wiring/connector	Restart the system once at the breaker
51-02	Outdoor air temperature (OAT) thermistor shorted (resistance too low) pro repair	Shorted/failed outdoor air thermistor; Pinched or chafed sensor wiring	Restart the system once at the breaker
52-01	Outdoor coil temperature (OCT) thermistor open (resistance too high) — this sensor controls the defrost cycle pro repair	Open/failed outdoor coil thermistor; Sensor knocked off the coil tube; Damaged sensor wiring/connector	Clear ice and snow from the outdoor coil; Restart the system once at the breaker
52-02	Outdoor coil temperature (OCT) thermistor shorted (resistance too low) — this sensor controls the defrost cycle pro repair	Shorted/failed outdoor coil thermistor; Pinched or chafed sensor wiring	Clear ice and snow from the outdoor coil; Restart the system once at the breaker
53-41	Outdoor suction temperature (OST) thermistor open — heating is locked out, backup heat only pro repair	Open/failed suction thermistor; Disconnected or damaged sensor wiring	Confirm backup/auxiliary heat is keeping the home warm; Restart the system once at the breaker
53-42	Outdoor suction temperature (OST) thermistor shorted — backup heat only pro repair	Shorted/failed suction thermistor (resistance below ~1k ohm); Pinched or chafed sensor wiring	Confirm backup/auxiliary heat is keeping the home warm; Restart the system once at the breaker
54-01	Outdoor discharge temperature (ODT) thermistor open — system runs at start-up speed only pro repair	Open/failed discharge thermistor; Disconnected or damaged sensor wiring	Restart the system once at the breaker
54-02	Outdoor discharge temperature (ODT) thermistor shorted — system runs at start-up speed only pro repair	Shorted/failed discharge thermistor; Pinched or chafed sensor wiring	Restart the system once at the breaker
61-13	Reversing valve timeout fault — the reversing valve could not switch between heating and cooling within about 10 minutes (heat pump only) pro repair	Stuck or sticking reversing valve; Reversing valve coil weak or failing; Low refrigerant charge preventing the valve from shifting	Restart the system once at the breaker; If the unit blows cold air in heating or warm air in cooling, note it for the technician
61-41	Reversing valve solenoid (RVS) open lockout — the reversing valve coil reads open / infinite resistance (heat pump only) pro repair	Open or burned-out reversing valve solenoid coil; Broken or disconnected coil wiring; Control board output fault	Restart the system once at the breaker; if it locks out again, call a technician
61-53	Reversing valve timeout lockout — the reversing valve timeout fault occurred 4 times in 2 hours, triggering a 2-hour lockout (heat pump only) pro repair	Repeatedly stuck reversing valve; Failing reversing valve coil; Persistent low refrigerant charge	Wait out the lockout, then restart once at the breaker; if it returns, call a technician
62-01	Pressure equalization valve (PEV) solenoid open — the PEV coil reads open / infinite resistance (system may continue if pressures are acceptable) pro repair	Open or failed PEV solenoid coil; Disconnected or damaged coil wiring	Restart the system once at the breaker
38-13	Variable-frequency-drive (VFD) compressor fault — compressor start failure pro repair	Compressor failed to start (locked rotor, low voltage, or pressure imbalance); Inverter/VFD fault; Wiring fault to the compressor	Confirm the breaker and disconnect are on; Clear snow/debris from the outdoor unit; Restart the system once at the breaker
39-13	Outdoor fan motor start failure pro repair	Outdoor fan blade jammed by ice or debris; Failed outdoor fan motor or VFD; Fan wiring fault	With the unit OFF at the disconnect, clear ice/snow/leaves from around the fan (do not touch internal wiring); Restart the system once at the breaker

Carrier heat pump codes we get called for most

16 — Communication with the user interface / Infinity thermostat lost (2-stage Infinity/Performance flash-code system)

Typical causes include damaged or loose abcd communication wiring between outdoor unit, indoor unit and thermostat; reversed or miswired communication terminals; failed outdoor control board or thermostat. A few things are safe to check yourself (Confirm the thermostat screen is on and the breaker/disconnect is on; Restart the system once at the breaker), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 16 on Carrier heat pumps throughout Greater Vancouver.

53 — Outdoor air temperature (OAT) sensor fault

Typical causes include failed outdoor air thermistor; disconnected or damaged sensor wiring; sensor out of resistance range. A few things are safe to check yourself (Restart the system once at the breaker), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 53 on Carrier heat pumps throughout Greater Vancouver.

71 — Low-stage compressor thermal cutout (internal overload on the low-stage / first-stage compressor opened)

Typical causes include compressor overheating from low airflow or dirty coils; low or high refrigerant pressure; failing compressor. A few things are safe to check yourself (Replace a dirty filter and clear debris/snow from the outdoor unit; Allow the unit time to cool down), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 71 on Carrier heat pumps throughout Greater Vancouver.

31 — High-pressure switch open (refrigerant high-side pressure too high)

Typical causes include dirty or blocked outdoor coil (cooling) or indoor coil/airflow restriction (heating); dirty air filter or closed registers reducing airflow; outdoor fan motor failure. A few things are safe to check yourself (Replace or clean a dirty air filter; Clear snow, ice, leaves and debris from around the outdoor unit), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 31 on Carrier heat pumps throughout Greater Vancouver.

Is it safe to keep running a Carrier heat pump with a fault code?

Most Carrier fault codes put the heat pump into a safe lockout for a reason. You can safely check the basics — the power and breaker on, the indoor filter clean, the outdoor unit clear of snow, ice and debris, and the remote set to the correct mode and temperature — and restart it once. If the code returns, stop and book a technician. Mini-split and heat-pump faults are electrical and refrigerant issues — never open the indoor or outdoor unit, and never touch the wiring or refrigerant lines yourself.

Carrier heat pump repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Carrier heat pumps — sensor and thermistor errors, indoor-to-outdoor communication faults, fan and compressor problems, refrigerant and pressure faults, and control-board issues — including units we didn’t install. We’re brand-agnostic, carry common parts, and give you an honest repair-or-replace assessment with upfront pricing and a free estimate. If your heat pump is beyond economical repair, we’ll show you right-sized, high-efficiency replacement options and the rebates available.

Need it sorted fast? We offer priority emergency heat pump repair. Explore Heat Pump services, browse all heat pump error codes by brand, or request a free estimate.

Carrier heat pump service areas

We repair Carrier heat pumps across Greater Vancouver and the Fraser Valley, including:

Carrier heat pump error code FAQs

Can I reset my Carrier heat pump myself?

Yes — power-cycling the unit at the breaker once is generally safe after you’ve checked the basics (the power and breaker on, the indoor filter clean, the outdoor unit clear of snow, ice and debris, and the remote set to the correct mode and temperature). If the heat pump faults again right away, stop and note the code — repeatedly resetting a heat pump that keeps locking out can mask a real problem. Call a licensed HVAC technician to diagnose it.

What does the Carrier 16 code mean?

On Carrier heat pumps, 16 commonly indicates communication with the user interface / infinity thermostat lost (2-stage infinity/performance flash-code system). Confirm the exact meaning against your unit’s manual — codes can vary by model and series — and have the repair done by a licensed HVAC technician. HeatLand fixes this across Greater Vancouver.

Do you repair Carrier heat pumps you didn’t install?

Yes. HeatLand is brand-agnostic and services Carrier heat pumps throughout Metro Vancouver and the Fraser Valley, whether or not we installed the unit. We carry common parts and give you an honest repair-or-replace assessment.

Is a Carrier heat pump fault code an emergency?

No heat in cold weather or no cooling in a heat wave is worth treating urgently. For priority heat pump repair across Greater Vancouver, call (604) 330-3812.

How much does Carrier heat pump repair cost in Vancouver?

It depends on the fault. Many Carrier codes point to sensors, thermistors, capacitors or control parts — usually far cheaper than replacement. We give upfront pricing and a free estimate before any work.

More Heat Pump error-code guides

HeatLand repairs every major heat pump brand across Greater Vancouver. More brand guides: