Carrier heat pumps report faults in different ways depending on the model. Infinity systems flash a two-digit code on an amber light inside the outdoor unit and show it on the Infinity wall control. Newer Infinity Greenspeed units use two-part codes such as 31-58. Many Comfort and Performance heat pumps show no code at all, and Carrier ductless units use letter codes such as E1 or P0. This guide lists the Carrier heat pump error codes for each family, what they mean, which lights aren’t faults, how lockouts clear and what repairs usually cost.
The meanings come from Carrier’s own installation instructions and service manuals for the Infinity 25HNB6/9, 25VNA8, 25VNA0 and 25VNA4 heat pumps and the 40MAQ ductless system. Carrier has changed what some numbers mean between generations, so check the model number on your outdoor unit’s rating plate before you read the tables.
Table of Contents
First, find your model number
| Carrier family | Example models | How faults show |
|---|---|---|
| Infinity two-stage | 25HNB6, 25HNB9 | Two-digit flash code on the outdoor board and on the Infinity control |
| Infinity variable speed, older | 25VNA8 (Infinity 18VS), original 25VNA0 (Infinity 20 Greenspeed) | Two-digit flash code on the outdoor board and on the Infinity control |
| Infinity Greenspeed, current | 25VNA4 (Infinity 24), 24VNA6 | Two-digit flash on the board; the full two-part code, such as 31-58, on the Infinity control |
| Comfort and Performance | 25HCE4, 25HBC5, 25HCB3, 25HCC5, 25HCB6 | Usually no code; the outdoor unit simply stops |
| Ductless | 40MAQ indoor with 38MAQ or 38MGQ outdoor | Letter code on the indoor display, or flashing lamps |
How to read the flash code
On Infinity outdoor units, the amber STATUS light flashes the code in two parts. Short flashes give the first digit and long flashes give the second, so 3 short flashes followed by 2 long ones is code 32. The code repeats after a pause of about 2.5 seconds. Only the most recent, highest-priority code is shown, and the Infinity wall control keeps a fault history under its service menu.
Lights that aren’t faults
- Amber light on steady, no flashing: standby, with no call to run.
- 1 or 2 flashes, repeating: running. On two-stage units, 1 is low stage and 2 is high stage. On variable-speed units, 1 flash means variable-capacity operation.
- Code 68 on older variable-speed units: a warm-up after a power cut. On the 25VNA8 it lasts 10 minutes, and on the 25VNA0 compressor sump heating can take up to 2 hours. Carrier says no action is needed.
- Continuous flashing on a 25VNA0: emergency mode. The unit runs at nominal capacity because it can’t detect the Infinity control.
- No heat for up to about 10 minutes in cold weather: usually defrost, which isn’t a fault.
Carrier Infinity two-digit codes
These codes mean the same thing on the 25HNB6/9 two-stage units and the older 25VNA8 and 25VNA0 variable-speed units, unless the table says otherwise.
| Code | What it means | What happens |
|---|---|---|
| 16 | Lost communication with the Infinity control | Check the control and the wiring |
| 25 | Invalid or missing model plug | Unit won’t run |
| 31 | High-pressure switch open | Short delay, then a retry; repeated trips lead to 84 |
| 32 | Low-pressure trip | Short delay, then a retry; repeated trips lead to 83 |
| 46 | Brown-out: supply voltage too low | Runs again when voltage recovers |
| 48 | Lost inverter communication (variable speed) | System malfunction |
| 53 | Outdoor air temperature sensor fault | Sensor or wiring check |
| 54 | Suction temperature sensor fault (variable speed) | Sensor or wiring check |
| 55 | Outdoor coil temperature sensor fault | Sensor or wiring check |
| 56 | Outdoor air and coil sensor readings out of range | Sensor, wiring or reversing valve check |
| 57 | Suction pressure sensor fault (variable speed) | Sensor or wiring check |
| 69 | Inverter or compressor internal fault (variable speed) | System malfunction |
| 82 | Suction over-temperature lockout (variable speed) | 4-hour lockout |
| 83 | Low-pressure lockout | 4-hour lockout |
| 84 | High-pressure lockout (see our Carrier code 84 guide) | 4-hour lockout |
| 95 | High current lockout (variable speed) | 2-hour lockout |
| 96 / 97 | DC under-voltage / over-voltage lockout (variable speed) | 2-hour lockout |
| 98 / 99 | High torque / high torque lockout (variable speed) | 99 locks out for 2 hours |
Codes that change meaning by model
- 45: outdoor control board failed on the 25HNB6/9; compressor winding fault (grounded compressor) on the 25VNA0.
- 49: compressor over-current on the 25VNA8; a 230-volt dropout reset on the 25VNA0.
- 71 and 72: compressor thermal cutout in low or high stage on the 25HNB6/9. On the variable-speed units, 71 is a compressor dropout or motor temperature event and 72 is suction over-temperature.
- 74: no 230 volts at the compressor (contactor open) on the 25HNB6/9; discharge temperature lockout on the 25VNA8.
- 81 and 82: on the 25HNB6/9, thermal lockouts after three compressor cutouts in a row, lasting 4 hours.
- 88: compressor or inverter lockout on the 25VNA8; inverter temperature lockout on the 25VNA0.
Current Infinity Greenspeed two-part codes
The 25VNA4 (Infinity 24) and 24VNA6 show a two-part code on the Infinity control. The first part is the fault and the second describes the action: as a rule, codes ending in 11, 15 or 16 limit or stop the unit for a short time, and codes ending in 53, 55 or 58 are lockouts. These are the codes homeowners are most likely to see:
| Code | What it means | Lockout |
|---|---|---|
| 13 | System control upgrade recommended or required | Until the control is updated |
| 14-94 / 15-94 | Line voltage low / high | Clears when voltage is normal |
| 18-11 | Indoor coil freeze protection, speed reduced | None |
| 31-11 / 31-16 | High pressure: capacity limited / unit shut down | None |
| 31-58 | High-pressure lockout | 2 hours |
| 32-55 | Low suction pressure lockout | 2 hours |
| 32-59 | Low pressure disable, likely a refrigerant leak | Needs service |
| 34-58 | Compressor high-temperature lockout | 2 hours |
| 38-53 | Compressor failed to start three times | 2 to 4 hours (Carrier’s documents differ) |
| 39-53 / 39-58 | Outdoor fan failed to start / fan motor failure | 1 hour / 30 minutes |
| 41-13 | Defrost took too long | None |
| 61-53 | Reversing valve timeout | 2 hours |
| 82-55 | Power dropout at the drive | 2 hours |
| 84-58 | Drive (VFD) heat sink overheating | 2 hours |
| 86-46 | Drive communication fault | 1 hour |
84 isn’t always high pressure. On the older Infinity units, 84 is the 4-hour high-pressure lockout. On the 25VNA4 and 24VNA6, 84-58 is a drive overheating fault, and the high-pressure lockout is 31-58. Read the full code on the Infinity control before you act on it.
Comfort and Performance heat pumps: usually no code
The installation instructions for Carrier’s Comfort and Performance heat pumps that we reviewed don’t describe any fault codes on the defrost board. On these units, the high- and low-pressure switches simply break the signal to the contactor, so the outdoor unit stops without showing a code. Two normal delays can look like a fault: a 5-minute compressor time guard after each cycle, and a 5-minute lockout on the defrost board after any power interruption. If the outdoor unit still hasn’t started after 10 minutes with the thermostat calling for heat, it’s time for a technician.
Carrier ductless mini split codes
These codes come from Carrier’s service manual for the 40MAQ indoor unit paired with 38MAQ or 38MGQ outdoor units. Units without a display flash a lamp instead: the number of flashes, together with whether the timer lamp is lit, identifies the code. Other Carrier ductless lines can use different codes, so check your manual.
| Code | What it means |
|---|---|
| E0 | Indoor memory (EEPROM) error |
| E1 | Indoor and outdoor units not communicating |
| E2 | Zero-crossing signal error (power signal) |
| E3 | Indoor fan speed out of control |
| E4 | Room temperature sensor open or shorted |
| E5 | Indoor coil sensor open or shorted |
| EC | Refrigerant leak detected |
| F0 | Overload current protection |
| F1 | Outdoor air sensor open or shorted |
| F2 | Outdoor coil sensor open or shorted |
| F3 | Compressor discharge sensor open or shorted |
| F4 | Outdoor memory (EEPROM) error |
| F5 | Outdoor fan speed out of control |
| P0 | Inverter module (IPM) fault or overcurrent |
| P1 | Voltage too high or too low |
| P2 | Compressor top too hot (9,000 and 12,000 BTU sizes) |
| P4 | Inverter compressor drive error |
On Carrier multi-zone air handlers, “–” on the display means two indoor units are asking for opposite modes, and a lit PRE-DEF light means the unit is defrosting. Neither is a fault.
How lockouts clear and how to reset
- Infinity two-stage (25HNB6/9): after three high- or low-pressure trips in a row, the unit locks out for 4 hours. The lockout clears when the time is up or when the 24-volt control power is switched off and on.
- Infinity variable speed: lockouts last from 30 minutes to 4 hours depending on the code. Carrier says some conditions may need the outdoor unit’s power switched off for at least 2 minutes to clear. After storms, voltage lockouts (95 to 97) should clear on their own once the weather settles.
- Ductless (40MAQ): Carrier’s troubleshooting steps start with switching the power off, waiting 2 minutes (10 minutes for P2) and restarting.
Clearing the fault history on the Infinity control doesn’t fix anything. If the same code returns after a reset, the cause is still there. Resetting a pressure lockout again and again just puts the system back into the conditions it was protecting itself from.
What you can safely check yourself
- Clear and rinse the outdoor coil. A dirty or blocked outdoor coil is one of the causes Carrier lists for high-pressure codes 31, 84 and 31-58 in cooling.
- Replace the filter and open supply registers. Low indoor airflow is a cause Carrier lists for low-pressure codes (32, 83, 32-55) and for 18-11.
- Check the outdoor fan. With the power off, make sure ice, snow or debris isn’t blocking the blades (fan codes 39-xx and 76).
- Check the breakers after a storm, and give voltage codes time to clear.
- Write down the code and the model number before you reset anything.
Refrigerant work, pressure switches, sensors, boards and the drive are jobs for a licensed technician. If the outdoor unit is covered in ice, see our frozen heat pump guide. If it keeps starting and stopping without a code, see heat pump short cycling.
What Carrier repairs usually cost
| Repair | Codes that can lead to it | Typical cost |
|---|---|---|
| Diagnostic visit | Any | $75–$250 |
| Control board | 45 (two-stage), E0, F4 | $150–$700 |
| Outdoor fan motor | 39-xx, 76, F5 | $200–$700 |
| Refrigerant leak repair and recharge | 32, 83, 32-59, EC | $300–$1,200 |
| Expansion valve (TXV/EXV) | 32, 83, 82 | $250–$800 |
| Reversing valve | 56, 61-53 | $200–$650 |
| Compressor | 69, 88, 38-53 (once other causes are ruled out) | $650–$2,400 |
Ranges come from Angi’s heat pump repair data (October 2026), with the diagnostic visit and expansion valve from Fixr (January 2026). Which codes lead to which repair is our grouping, based on the causes Carrier lists for each code. The main cost guides don’t price pressure switches or sensors. The parts are usually inexpensive, but replacing a pressure switch on a sealed system can also mean recovering the refrigerant.
Is it covered by the warranty?
On Carrier’s warranty page, registering within 90 days of installation lets you choose a 10-year parts limited warranty or, where the dealer takes part, 5 years on parts plus 3 years on labor. Without registration, the standard warranty is 5 years on parts. In places where registration can’t be a condition by law, the 10-year parts warranty applies automatically. The parts warranty doesn’t cover labor or refrigerant, and the choice of plans doesn’t apply to new construction. Check the warranty certificate for your model, because terms vary by product and date.
Frequently asked questions
What does code 84 mean on a Carrier heat pump?
On older Infinity units such as the 25HNB6/9, 25VNA8 and original 25VNA0, 84 is a 4-hour high-pressure lockout. On the current 25VNA4 and 24VNA6, 84-58 means the variable-speed drive is overheating. Our Carrier code 84 guide explains the high-pressure version.
What does code 31 mean on a Carrier?
31 means the high-pressure switch has opened. The unit waits and tries again. If it keeps happening, the control escalates to a high-pressure lockout: 84 on older Infinity units, 31-58 on current Greenspeed units.
What is code 83 on a Carrier Infinity?
83 is the low-pressure lockout on two-digit Infinity units. It follows repeated low-pressure trips (code 32), and the unit stays off for 4 hours. Low refrigerant and poor indoor airflow are among the causes Carrier lists.
Why does my Carrier heat pump show no code?
Many Comfort and Performance heat pumps don’t display fault codes. Their pressure switches simply stop the outdoor unit. Wait 10 minutes for the normal time delays, then call a technician if it still won’t start.
How do I reset a Carrier heat pump?
On a two-stage Infinity unit, a pressure lockout clears after 4 hours or when the 24-volt control power is switched off and on. On variable-speed units, Carrier says switching the outdoor unit’s power off for at least 2 minutes may be needed. If the code comes back, call a technician.
Sources
- Carrier, Installation Instructions, Infinity 2-Stage Heat Pump 25HNB6/25HNB9, 25HNB6-9-6SI (March 2015)
- Carrier, Service Manual, 25VNA8 Infinity 18VS Variable Speed Heat Pump
- Carrier, Service Manual, 24VNA0 / 25VNA0 Infinity Variable Speed with Greenspeed Intelligence
- Carrier, Installation Instructions, 25VNA4 Infinity Variable Speed Heat Pump, 25VNA4-03SI (February 2021)
- Carrier, Service Manual, 24VNA6 / 25VNA4
- Carrier, Installation Instructions, Performance Series Heat Pump 25HCB3/25HCC5, 25HCB-C-6SI (December 2012)
- Carrier, Installation Instructions, 25HCB6 Performance two-stage heat pump, 25HCB6-5SI (March 2015)
- Carrier, Service Manual, 40MAQ High Wall Ductless System, 40MAQ-01SM (August 2016)
- Carrier, Owner’s Manual, 40MUAA air handler, OM-40MUAA-02 (August 2023)
- Carrier, Infinity System Control Installation Instructions
- Carrier, Warranty (homeowner resources)
- Angi, Heat Pump Repair Cost (October 2026)
- Fixr, Heat Pump Repair Cost (January 2026)