Carrier Air Conditioner Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your Carrier air conditioner? This guide explains what the most common Carrier air conditioner error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed HVAC technicians for Carrier air conditioner 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 air conditioner error codes

On Infinity/Evolution communicating systems, faults appear as 2- or 3-digit numbers on the Infinity Touch wall control (Menu > Service > Fault History). On the outdoor unit control board, the same numeric codes are shown by the amber status LED: short flashes give the first digit and long flashes give the second digit (a short flash is ~0.25 s ON, a long flash is ~1.0 s ON). Solid-on means standby/no call; rapid continuous flashing means the unit is running on standard thermostat (emergency/non-communicating) inputs. Basic single-stage Comfort/Performance ACs with a standard thermostat have no on-board code display.

Carrier air conditioner error codes & what they mean

These are the Carrier air conditioner 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 error / communication loss between the outdoor unit (air conditioner or heat pump) and the system. The outdoor control cannot communicate with the Infinity/Evolution wall control or indoor unit pro repair	Loss of 24V communication signal on the A/B/C/D data wires; Loose, corroded, or miswired low-voltage connections; Damaged or pinched thermostat/communication cable	Confirm the outdoor disconnect and the breaker are switched on; Set the thermostat to Cool and lower the setpoint to confirm a cooling call; Try a single power-cycle at the breaker, wait a few minutes, then restart
25	Invalid model plug / invalid model. The model-identification plug on the outdoor control board is missing, wrong, or unreadable, so the control cannot configure the unit pro repair	Missing or incorrect model plug after a board replacement; Damaged model plug; Failed control board	Confirm the disconnect and breaker are on; Try a single power-cycle at the breaker, wait a few minutes, then restart
31	High pressure switch open. The refrigerant high-pressure switch has tripped, indicating excessive system pressure pro repair	Dirty or blocked outdoor condenser coil; Restricted airflow over the outdoor coil; Outdoor fan not running	Clear leaves, grass, and debris away from the outdoor condenser unit and make sure airflow around it is unobstructed; Replace or clean a dirty indoor air filter; Confirm the disconnect and breaker are on
32	Low pressure switch open. The refrigerant low-pressure switch has tripped, indicating low system pressure pro repair	Low refrigerant charge / refrigerant leak; Restricted indoor airflow (dirty filter, blocked coil); Failed low-pressure switch	Replace or clean a dirty indoor air filter; Make sure supply and return vents are open and unblocked; Confirm the thermostat is set to Cool
45	Control fault. An internal fault was detected in the outdoor unit control board pro repair	Failed or faulty outdoor control board; Power-supply / voltage irregularity affecting the control	Confirm the disconnect and breaker are on; Try a single power-cycle at the breaker, wait a few minutes, then restart
46	Brownout on 230V. Incoming line voltage dropped below the acceptable threshold (approximately below 187V) for a sustained period pro repair	Utility low-voltage / brownout condition; Undersized or loose line-voltage wiring; Overloaded electrical circuit	Check whether other appliances/lights are also dimming or losing power (possible utility issue); Confirm the disconnect and breaker are on; Try a single restart once normal power is confirmed
47	No 230V to unit. Line voltage (230V) is not present at the outdoor unit / contactor pro repair	Outdoor disconnect pulled or off; Tripped breaker; Blown fuse at the disconnect	Confirm the outdoor disconnect switch is fully engaged (on); Reset the breaker once if it is tripped; Try a single restart after power is restored
53	Outdoor air temperature sensor fault. The outdoor air temperature (OAT) sensor reading is out of range or has failed pro repair	Failed or disconnected outdoor air temperature thermistor; Loose or corroded sensor connection; Damaged sensor wiring	Confirm the disconnect and breaker are on; Try a single restart
55	Outdoor coil temperature sensor fault. The outdoor coil temperature sensor reading is out of range or has failed pro repair	Failed or disconnected outdoor coil thermistor; Loose or corroded sensor connection; Damaged sensor wiring	Confirm the disconnect and breaker are on; Try a single restart
56	Temperature sensor out of range / thermistors out of range. The outdoor temperature sensors show an improper or inconsistent relationship to each other pro repair	One or more outdoor thermistors out of calibration or failed; Sensor mounting or wiring problem	Confirm the disconnect and breaker are on; Try a single restart
71	Thermal cutout in low stage. The compressor internal overload (thermal protector) tripped while running in low stage pro repair	Compressor overheating; Dirty outdoor condenser coil / restricted airflow; Outdoor fan problem	Clear debris from around the outdoor condenser and ensure airflow is unobstructed; Replace or clean a dirty indoor air filter; Allow the unit to cool, then try a single restart
72	Thermal cutout in high stage. The compressor internal overload (thermal protector) tripped while running in high stage pro repair	Compressor overheating; Dirty outdoor condenser coil / restricted airflow; Outdoor fan problem	Clear debris from around the outdoor condenser and ensure airflow is unobstructed; Replace or clean a dirty indoor air filter; Allow the unit to cool, then try a single restart
73	Contactor shorted. Compressor voltage was sensed when the contactor should be open (contactor stuck closed / welded) pro repair	Welded or stuck-closed contactor; Failed contactor; Control board fault	Confirm the disconnect and breaker are on; Do not open the unit; call a technician
74	No 230V at compressor. Line voltage is not being sensed at the compressor (two-capacity / communicating outdoor units) pro repair	Failed contactor not closing; Open compressor circuit or wiring; Blown internal fuse	Confirm the disconnect and breaker are on; Try a single restart after confirming power
75	Low-stage did not start / low speed no start. The compressor failed to start in low stage when commanded pro repair	Failed start components; Seized or faulty compressor; Open winding or wiring	Confirm the disconnect and breaker are on; Try a single restart
76	Low-stage did not start 3 times / low-stage repeat no start. Low stage failed to start repeatedly and the stage is locked out (about 30 minutes) pro repair	Persistent start failure; Faulty compressor or start components; Electrical supply problem	Confirm the disconnect and breaker are on; Wait for the lockout to clear, then try a single restart
77	High-stage did not start / high speed no start. The compressor failed to start in high stage when commanded pro repair	Failed start components; Faulty compressor; Open winding or wiring	Confirm the disconnect and breaker are on; Try a single restart
78	High-stage did not start 3 times / high-stage repeat no start. High stage failed to start repeatedly and the stage is locked out (about 30 minutes) pro repair	Persistent start failure; Faulty compressor or start components; Electrical supply problem	Confirm the disconnect and breaker are on; Wait for the lockout to clear, then try a single restart
81	Thermal lockout in low stage. After repeated low-stage thermal cutouts, low stage is locked out for about 4 hours pro repair	Repeated compressor overheating; Dirty condenser coil / airflow restriction; Charge or electrical fault	Clear debris from around the outdoor condenser; Replace or clean a dirty indoor air filter; Allow the lockout to expire; if it returns, call a technician
82	Thermal lockout in high stage. After repeated high-stage thermal cutouts, high stage is locked out for about 4 hours pro repair	Repeated compressor overheating; Dirty condenser coil / airflow restriction; Charge or electrical fault	Clear debris from around the outdoor condenser; Replace or clean a dirty indoor air filter; Allow the lockout to expire; if it returns, call a technician
83	Low-pressure lockout (4 hours). After repeated low-pressure switch trips, the unit is locked out for about 4 hours pro repair	Low refrigerant charge / leak; Restricted indoor airflow; Repeated low-pressure trips	Replace or clean a dirty indoor air filter; Make sure vents are open and unblocked; Allow the lockout to expire; if it returns, call a technician
84	High-pressure lockout (4 hours). After repeated high-pressure switch trips, the unit is locked out for about 4 hours pro repair	Dirty/blocked outdoor condenser coil; Restricted condenser airflow or failed outdoor fan; Overcharge or non-condensables	Clear leaves, grass, and debris away from the outdoor condenser and ensure airflow is unobstructed; Replace or clean a dirty indoor air filter; Allow the lockout to expire; if it returns, call a technician
85	Low contactor open. The low-stage contactor circuit is sensed open when it should be closed (two-capacity / communicating outdoor units) pro repair	Failed or stuck-open contactor; Open control wiring; Control board fault	Confirm the disconnect and breaker are on; Do not open the unit; call a technician
87	High contactor open. The high-stage contactor circuit is sensed open when it should be closed (two-capacity / communicating outdoor units) pro repair	Failed or stuck-open contactor; Open control wiring; Control board fault	Confirm the disconnect and breaker are on; Do not open the unit; call a technician
178	Wall control – indoor unit communication fault. The Infinity/Evolution wall control has lost communication with the indoor furnace or fan coil. Communicating systems only pro repair	Loose or corroded communication wiring between wall control and indoor unit; Blown indoor 24V fuse; Failed indoor control board	Confirm the indoor unit (furnace/air handler) breaker and switch are on; Confirm the thermostat/wall control screen is powered; Try a single power-cycle at the breaker, wait a few minutes, then restart
179	Wall control – outdoor communication fault. The Infinity/Evolution wall control has lost communication with the outdoor unit (air conditioner or heat pump). Communicating systems only pro repair	Loose, corroded, or miswired communication wiring to the outdoor unit; Loss of power to the outdoor unit; Failed outdoor control board	Confirm the outdoor disconnect and breaker are on; Set the thermostat to Cool to confirm a cooling call; Try a single power-cycle at the breaker, wait a few minutes, then restart
187	Wall control – low room temperature alert. The wall control is reporting an unusually low indoor temperature. Communicating systems only pro repair	Heating not keeping up or system off in cold weather; Cooling running when heating is needed; Sensor location issue	Confirm the thermostat mode and setpoint are correct for the season; Replace or clean a dirty indoor air filter; Confirm the system has power and try a single restart
188	Wall control – high room temperature alert. The wall control is reporting an unusually high indoor temperature, often present when cooling is not keeping up. Communicating systems only pro repair	Air conditioner not cooling / not running; Dirty filter or blocked outdoor condenser reducing capacity; Refrigerant or compressor problem	Set the thermostat to Cool and lower the setpoint; Replace or clean a dirty indoor air filter; Clear debris from around the outdoor condenser and ensure airflow is unobstructed
194	Wall control – possible frozen coil. The system detected conditions consistent with a frozen indoor evaporator coil. Communicating systems only pro repair	Severely restricted airflow (very dirty filter, closed vents, blocked return); Low refrigerant charge; Blower problem	Replace or clean a dirty indoor air filter; Make sure all supply and return vents are open and unblocked; Turn the system to Off (or Fan-only if available) to let the coil thaw, then restart once

Carrier air conditioner codes we get called for most

16 — Communication error / communication loss between the outdoor unit (air conditioner or heat pump) and the system. The outdoor control cannot communicate with the Infinity/Evolution wall control or indoor unit

Typical causes include loss of 24v communication signal on the a/b/c/d data wires; loose, corroded, or miswired low-voltage connections; damaged or pinched thermostat/communication cable. A few things are safe to check yourself (Confirm the outdoor disconnect and the breaker are switched on; Set the thermostat to Cool and lower the setpoint to confirm a cooling call), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 16 on Carrier air conditioners throughout Greater Vancouver.

53 — Outdoor air temperature sensor fault. The outdoor air temperature (OAT) sensor reading is out of range or has failed

Typical causes include failed or disconnected outdoor air temperature thermistor; loose or corroded sensor connection; damaged sensor wiring. A few things are safe to check yourself (Confirm the disconnect and breaker are on; Try a single restart), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 53 on Carrier air conditioners throughout Greater Vancouver.

71 — Thermal cutout in low stage. The compressor internal overload (thermal protector) tripped while running in low stage

Typical causes include compressor overheating; dirty outdoor condenser coil / restricted airflow; outdoor fan problem. A few things are safe to check yourself (Clear debris from around the outdoor condenser and ensure airflow is unobstructed; Replace or clean a dirty indoor air filter), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 71 on Carrier air conditioners throughout Greater Vancouver.

31 — High pressure switch open. The refrigerant high-pressure switch has tripped, indicating excessive system pressure

Typical causes include dirty or blocked outdoor condenser coil; restricted airflow over the outdoor coil; outdoor fan not running. A few things are safe to check yourself (Clear leaves, grass, and debris away from the outdoor condenser unit and make sure airflow around it is unobstructed; Replace or clean a dirty indoor air filter), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 31 on Carrier air conditioners throughout Greater Vancouver.

Is it safe to keep running a Carrier air conditioner with a fault code?

Most Carrier fault codes put the air conditioner into a safe lockout for a reason. You can safely check the basics — the power and breaker on, the air filter clean, the outdoor condenser clear of debris, and the thermostat set to cool — and restart it once. If the code returns, stop and book a technician. Air-conditioner faults are electrical and refrigerant issues — never open the unit or touch the wiring or refrigerant lines yourself.

Carrier air conditioner repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Carrier air conditioners — sensor and thermistor errors, 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 air conditioner 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 air conditioner repair. Explore Air Conditioner services, browse all air conditioner error codes by brand, or request a free estimate.

Carrier air conditioner service areas

We repair Carrier air conditioners across Greater Vancouver and the Fraser Valley, including:

Carrier air conditioner error code FAQs

Can I reset my Carrier air conditioner 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 air filter clean, the outdoor condenser clear of debris, and the thermostat set to cool). If the air conditioner faults again right away, stop and note the code — repeatedly resetting a air conditioner 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 air conditioners, 16 commonly indicates communication error / communication loss between the outdoor unit (air conditioner or heat pump) and the system. the outdoor control cannot communicate with the infinity/evolution wall control or indoor unit. 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 air conditioners you didn’t install?

Yes. HeatLand is brand-agnostic and services Carrier air conditioners 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 air conditioner fault code an emergency?

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

How much does Carrier air conditioner 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 Air Conditioner error-code guides

HeatLand repairs every major air conditioner brand across Greater Vancouver. More brand guides: