CARRIER ERROR CODES
Data Verified: January 2026
Professional diagnostic codes and troubleshooting steps.
Technical Note: CARRIER systems are part of a shared manufacturing platform. These codes are identical for BRYANT and PAYNE.
Normal Severity
12
Furnace - Blower on after Power-up
Troubleshooting Steps
- • Blower runs for 90 seconds if power is lost during a call for heat.
- • Check for recent power interruptions.
- • Verify thermostat settings.
Source Reference TIC 2019-0002
High Severity
13
Furnace – Limit Lockout
Troubleshooting Steps
- • Check for dirty air filters or blocked return air vents.
- • Verify blower motor operation and speed settings.
- • Inspect high-limit switch for proper operation.
Source Reference TIC 2019-0002
High Severity
14
Furnace – Ignition Lockout
Troubleshooting Steps
- • Check gas valve and igniter resistance.
- • Verify flame sensor cleanliness and positioning.
- • Ensure gas supply is active and unobstructed.
Source Reference TIC 2019-0002
High Severity
15
Furnace – Blower Lockout
Troubleshooting Steps
- • Check blower motor wiring and capacitor.
- • Verify motor is not seized or overheating.
- • Inspect control board for blower relay failure.
Source Reference TIC 2019-0002
High Severity
22
Furnace – Flame Sense Error
Troubleshooting Steps
- • Clean the flame sensor with light abrasive (steel wool).
- • Check for proper grounding of the burner assembly.
- • Verify flame is making direct contact with the sensor rod.
Source Reference TIC 2019-0002
Medium Severity
23
Furnace – LPS or HPS Fault
Troubleshooting Steps
- • Inspect Low Pressure Switch (LPS) and High Pressure Switch (HPS).
- • Check for blocked intake or exhaust venting.
- • Verify pressure switch tubing is clear of moisture or kinks.
Source Reference TIC 2019-0002
Critical Severity
24
Secondary Voltage Fuse Is Open
Troubleshooting Steps
- • Check the 3-amp fuse on the control board; replace if blown.
- • Inspect for a short circuit in the low-voltage thermostat wiring (check the outdoor unit contactor).
- • Verify no wires are pinched or touching the furnace chassis.
Source Reference TIC 2019-0002
High Severity
25
Invalid Model Selection
Troubleshooting Steps
- • Check that the model plug on the control board is present and correct.
- • Ensure the control board is the correct replacement part for this specific model.
- • Power cycle the system to see if the board re-recognizes the unit.
Source Reference TIC 2019-0002
High Severity
31
Pressure Switch Did Not Close or Reopened
Troubleshooting Steps
- • Check for a blocked flue vent, excessive wind, or disconnected pressure tubing.
- • Inspect the condensate line for clogs (common in high-efficiency units).
- • Verify the inducer motor is running at the correct speed.
Source Reference TIC 2019-0002
Medium Severity
32
Low-Heat Pressure Switch Did Not Close
Troubleshooting Steps
- • Check for restricted combustion air supply or plugged condensate drain.
- • Inspect pressure switch wiring and verify tubing is not sagging or holding water.
- • Verify low inlet gas pressure if using a Low Gas Pressure Switch (LGPS).
Source Reference TIC 2019-0002
High Severity
33
Limit Circuit Fault / Open Limit Switch
Troubleshooting Steps
- • Check for restricted airflow caused by a dirty filter or closed registers.
- • Inspect the blower motor to ensure it is moving enough air.
- • Check the limit switch and limit gasket for damage.
Source Reference TIC 2019-0002
High Severity
34
Ignition Proving Fault
Troubleshooting Steps
- • Clean the flame sensor with fine steel wool or a Scotch-Brite pad.
- • Check for proper grounding of the burner assembly and control board.
- • Verify the Hot Surface Ignitor (HSI) is glowing and positioned correctly.
Source Reference TIC 2019-0002
High Severity
41
Blower Motor Outside Valid Speed Range
Troubleshooting Steps
- • Check for physical obstructions in the blower wheel.
- • Verify the blower motor wiring harness is secure.
- • Check for high static pressure in the ductwork.
Source Reference TIC 2019-0002
High Severity
42
Inducer Motor Fault
Troubleshooting Steps
- • Check for a faulty inducer motor or a blocked vent pipe.
- • Inspect wiring connections between the inducer and the control board.
- • Verify the inducer motor capacitor is functional (if applicable).
Source Reference TIC 2019-0002
High Severity
44
Blower Motor Fault
Troubleshooting Steps
- • Inspect the blower motor for failure or loose wiring.
- • Check the control board for any burnt relays related to the blower.
- • Verify line voltage is reaching the motor.
Source Reference TIC 2019-0002
Critical Severity
45
Control Circuitry Lockout
Troubleshooting Steps
- • Reset power to clear the lockout; if it repeats, the control board likely needs replacement.
- • Check for a stuck-open gas valve relay on the board.
- • Verify there are no software check errors or flame sense circuit failures.
Source Reference TIC 2019-0002
Medium Severity
51
Blower Motor Communication Fault
Troubleshooting Steps
- • Check the communication wiring between the variable-speed blower and the control board.
- • Verify the motor has proper power and ground.
- • Replace the blower motor's control module if communication cannot be restored.
Source Reference TIC 2019-0002
High Severity
53
Outdoor Unit Communication Fault
Troubleshooting Steps
- • Check ABCD wiring between the indoor and outdoor control boards.
- • Verify the outdoor unit has 240V power and the transformer is outputting 24V.
- • Inspect for blown fuses on the outdoor inverter or start-up board.
Source Reference TIC 2019-0002
Medium Severity
54
Outdoor Inverter / Controller Board Temperature Sensor Fault
Troubleshooting Steps
- • Check the thermistor resistance on the inverter heat sink.
- • Ensure the heat sink is clear of debris and the cooling fan is operational.
- • Replace the inverter board if the sensor is integrated and failing.
Source Reference TIC 2019-0002
Normal Severity
55
Outdoor Ambient Temperature Sensor Fault
Troubleshooting Steps
- • Check the ambient thermistor for damage or disconnection.
- • Verify resistance against the manufacturer’s temperature chart.
- • System may default to 'backup' modes until the sensor is replaced.
Source Reference TIC 2019-0002
Medium Severity
56
Outdoor Evaporator / Coil Temperature Sensor Fault
Troubleshooting Steps
- • Inspect the coil sensor for proper mounting on the liquid line.
- • Check for corrosion at the plug-in connector on the board.
- • Replace sensor if resistance is open or shorted.
Source Reference TIC 2019-0002
Critical Severity
57
A2L Refrigerant Leak Detected (2026 Standard) / Pressure Switch Error
Troubleshooting Steps
- • A2L SAFETY: Evacuate the premises and ensure the indoor blower is running to ventilate gas.
- • Check A2L mitigation sensor for a 'Leak' trip status.
- • Check high/low pressure switch circuit if unit is a legacy R-410A model.
Source Reference TIC 2019-0002 / 2026 Truth Table
High Severity
58
Outdoor Discharge Temperature Sensor Fault
Troubleshooting Steps
- • Check the discharge line thermistor located on the compressor pipe.
- • Ensure the sensor hasn't slipped out of its thermal well/clip.
- • Verify refrigerant charge; high discharge temps can sometimes trigger sensor errors.
Source Reference TIC 2019-0002
High Severity
71
Compressor Thermal Cutout
Troubleshooting Steps
- • Allow compressor to cool for 2 hours; check for internal overload trip.
- • Verify outdoor fan motor is running and coil is clean.
- • Check for low refrigerant charge or non-condensables in the system.
Source Reference TIC 2019-0002
High Severity
72
Compressor Low Pressure Dropout
Troubleshooting Steps
- • Check for a refrigerant leak or a stuck-closed Electronic Expansion Valve (EEV).
- • Verify indoor airflow (dirty filter or blower failure).
- • Inspect the Low Pressure Switch (LPS) wiring.
Source Reference TIC 2019-0002
High Severity
73
Compressor High Pressure Dropout
Troubleshooting Steps
- • Check for a dirty outdoor coil or failed outdoor fan motor.
- • Verify the system is not overcharged with refrigerant.
- • Check for closed service valves or restrictions in the liquid line.
Source Reference TIC 2019-0002
Critical Severity
81
VFD (Variable Frequency Drive) Inverter Lockout
Troubleshooting Steps
- • Check the inverter power module for a short circuit.
- • Inspect the compressor windings for a ground fault.
- • Verify incoming line voltage is stable (within +/- 10%).
Source Reference TIC 2019-0002
Medium Severity
191
Wall Control - UI Error / Communication Lost
Troubleshooting Steps
- • Reset the Wall Control (Thermostat) by pulling it off the subbase for 10 seconds.
- • Check for a loose 'Green' or 'White' wire on the ABCD bus.
- • Update Wall Control firmware if available.
Source Reference TIC 2019-0002
Medium Severity
192
SAM – SAM Radio Test Failed
Troubleshooting Steps
- • Ensure the System Access Module (SAM) antenna is properly connected and not obstructed by metal.
- • Check for local 2.4GHz interference from other wireless devices.
- • Power cycle the SAM and re-initiate the radio test via the Wall Control.
Source Reference TIC 2019-0002
Medium Severity
193
SAM – SAM Profile Failed
Troubleshooting Steps
- • The SAM failed to download the equipment profile; check internet connectivity.
- • Verify that the SAM is registered correctly on the manufacturer's cloud portal.
- • Perform a factory reset on the SAM and re-bind it to the Wall Control.
Source Reference TIC 2019-0002
High Severity
194
Wall Control – Possible Frozen Coil
Troubleshooting Steps
- • Check for restricted airflow: replace dirty air filters and open all supply registers.
- • Inspect the indoor blower motor for proper operation.
- • Verify refrigerant charge levels; a low charge can cause the evaporator coil to freeze.
Source Reference TIC 2019-0002
Normal Severity
195
Wall Control – Utility Curtailment Event
Troubleshooting Steps
- • Informational only: The local utility company has remotely limited HVAC usage during peak demand.
- • System will return to normal operation once the utility event concludes.
- • Check settings in the Wall Control to opt-out of future events if desired.
Source Reference TIC 2019-0002
Medium Severity
196
Wall Control – Auxiliary Input (G) Shutdown
Troubleshooting Steps
- • Check the 'G' terminal input on the indoor control board for an active 24V signal.
- • This is often wired to a float switch or fire alarm; check for a tripped condensate pan switch.
- • Clear any water from the secondary drain pan if a float switch is present.
Source Reference TIC 2019-0002
High Severity
210
Wall Control – Excessive Static Pressure Encountered
Troubleshooting Steps
- • The system detected static pressure above 1.0" WC. Check for highly restrictive 'high-MERV' filters.
- • Inspect ductwork for collapsed sections, closed dampers, or undersized returns.
- • Verify that the total number of open registers is sufficient for the system's tonnage.
Source Reference TIC 2019-0002
Medium Severity
211
Wall Control – Zone 1 Airflow Limited / Stage Down
Troubleshooting Steps
- • The system has reduced capacity to protect itself because Zone 1 cannot handle the required airflow.
- • Check the Zone 1 damper for proper opening and verify the duct size for that zone.
- • Ensure the Zone 1 temperature sensor is not located near a heat source causing false calls.
Source Reference TIC 2019-0002
Medium Severity
212
Wall Control – Zone 2 Airflow Limited / Stage Down
Troubleshooting Steps
- • Check Zone 2 dampers and ductwork for restrictions.
- • Verify that the Zone 2 bypass damper (if used) is weighted correctly.
- • Ensure registers in Zone 2 are not blocked by furniture.
Source Reference TIC 2019-0002
High Severity
91
System Communication Fault (ABCD Bus)
Troubleshooting Steps
- • Check for a cross-wired ABCD connector (e.g., A wired to B).
- • Inspect for a loose data wire at the Indoor Control Board or Wall Control.
- • Ensure the communication wires are shielded or kept away from high-voltage lines.
Source Reference TIC 2019-0002
High Severity
178
VFD Inverter – Heat Sink Over-Temperature
Troubleshooting Steps
- • Verify the outdoor unit inverter cooling fan is rotating and clear of debris.
- • Inspect the thermal paste between the power module and the heat sink.
- • Check for high ambient conditions or direct sunlight heating the control box.
Source Reference TIC 2019-0002
Critical Severity
171
VFD Inverter – DC Bus Over-Voltage
Troubleshooting Steps
- • Check incoming line voltage; it may be exceeding the 253V limit.
- • Verify the compressor is not back-feeding voltage during a rapid shutdown.
- • Inspect the inverter board for damaged capacitors or surge protection components.
Source Reference TIC 2019-0002
High Severity
173
VFD Inverter – Compressor Phase Current Imbalance
Troubleshooting Steps
- • Measure the resistance of each compressor winding (U-V, V-W, W-U); they must be nearly identical.
- • Check for loose or corroded terminal connections at the compressor plug.
- • If windings are balanced, the inverter power module (IPM) is likely failing.
Source Reference TIC 2019-0002
High Severity
16
Communication Error (Indoor or Outdoor Unit)
Troubleshooting Steps
- • Check ABCD wiring for a short or break in the data lines.
- • Verify that the model plug is securely installed on the control board.
- • Inspect for interference from nearby high-voltage lines running parallel to the bus.
Source Reference TIC 2019-0002
Critical Severity
21
Gas Heat Lockout / Invalid Model Plug
Troubleshooting Steps
- • The control board does not recognize the furnace model. Check if the model plug is missing.
- • If a new board was installed, ensure it is the correct part number for this BTU rating.
- • Power cycle the unit to see if the board re-recognizes the model configuration.
Source Reference TIC 2019-0002
High Severity
35
Modulating Gas Valve Communication Fault
Troubleshooting Steps
- • Check the wiring harness between the main board and the modulating gas valve.
- • Verify the gas valve is receiving 24V power.
- • If wiring is intact, the modulating solenoid or the valve’s logic board may have failed.
Source Reference TIC 2019-0002