Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Carrier Infinity System Error Codes
The Carrier Infinity system is a fully communicating HVAC platform — the Infinity thermostat, furnace/air handler, and outdoor unit all talk over a proprietary 4-wire bus. Faults appear on the Infinity touch thermostat or wall control with specific codes identifying which component and what failed.
How the Infinity System Works
All components communicate on the Infinity bus:
- Infinity thermostat (SYSTXCCITC01-B, SYSTXCCWIC01-B) — system controller
- Gas furnace (58MVC, 58MVP, 59MN7) — indoor heat
- Air handler (FV4C, FX4D) — cooling coil + ECM blower
- Outdoor unit (24VNA, 24ACC, 25HCC) — compressor and condenser
Any loss of communication between these devices triggers a fault code.
Common Infinity Error Codes
| Code | Description | Likely Cause |
|---|---|---|
| 10 | System communication error | Wiring fault or device offline |
| 11 | Thermostat communication error | Thermostat board failure |
| 12 | Indoor unit communication error | Furnace/AHU board failure |
| 13 | Outdoor unit communication error | Outdoor board failure or power loss |
| 14 | Accessory communication error | Zone controller, humidifier offline |
| 24 | Secondary voltage fuse | 3A fuse blown on indoor board |
| 31 | High-pressure limit | Outdoor unit overpressure |
| 33 | Open limit device | Indoor high-limit tripped |
| 41 | Blower motor fault | ECM motor fault (Infinity blower) |
| 45 | Control voltage lockout | Low 24V supply |
| 46 | Low outdoor ambient | System in defrost lockout |
| 47 | Low indoor ambient | Heating system fault |
| 175 | Indoor board internal fault | Replace IFC board |
| 178 | Outdoor board internal fault | Replace outdoor control board |
Technician Tips
Carrier uses different diagnostic systems across furnaces, heat pumps, chillers, mini-splits, VRF equipment, rooftop units, and communicating controls. Confirm the full model number and whether the fault came from the indoor board, outdoor board, thermostat, or equipment controller before matching it to a repair path.
Start with power, wiring, airflow or water-flow, sensor, condensate, and safety-circuit checks before ordering control boards. If the same code returns after one reset and the basic cause is not obvious, test the named circuit instead of repeatedly cycling the equipment.
Common replacement parts for Carrier systems:
- Carrier flame sensor (part #HH18ZA641)
- Limit switch kit (part #HH18HA600)
- Pressure switch (part #HH18HA719)
Need Replacement Parts?
Before ordering, match the HVAC part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Code 10/11/12/13 — Communication Faults
These are the most common Infinity codes. They indicate a device on the bus isn’t responding.
Diagnosis Steps
Step 1 — Check power to all components. Furnace or air handler powered on? Outdoor unit circuit breaker on? Outdoor disconnect closed?
Step 2 — Inspect Infinity bus wiring. The bus uses 4 wires labeled 1, 2, 3, 4 on most Carrier boards. Inspect connections at:
- Thermostat base
- Furnace/AHU control board
- Outdoor unit control board
- Any zone damper boards or accessories
Connections must be secure. Bus wires run at data signal levels — a loose wire will drop the device.
Step 3 — Power cycle in order. Turn off the outdoor unit at the disconnect. Turn off the furnace at the power switch. Wait 2 minutes. Restore power: furnace first, then outdoor unit, then verify thermostat shows all devices connected.
Step 4 — Isolate the failed device. Disconnect the outdoor unit from the bus at the furnace board. If the thermostat now shows the indoor unit normally, the outdoor unit or its bus wiring is the fault.
Step 5 — Check for firmware updates. Infinity systems can have firmware mismatches after component replacement. Carrier’s Infinity dealer software (Infinity Dashboard) can check and update firmware for all connected components.
Code 41 — ECM Blower Motor Fault
The Infinity system uses a variable-speed ECM (Electronically Commutated Motor) blower. Code 41 means the motor reported an internal fault.
Common causes:
- Motor winding failure (requires replacement)
- Communication error between IFC and ECM module
- Voltage spike damage
The ECM is a two-part assembly: the motor and the control module. Replacing just the module (less expensive) fixes some code 41 faults. Full motor replacement costs $400–800+.
Code 33 — Open Limit (Overheating)
Code 33 on Infinity is the same as code 33 on standard Carrier furnaces — the high-limit switch opened because the heat exchanger overheated. Check:
- Air filter (dirty)
- Blower operation (code 41 causing this)
- Duct system restrictions
Dealer Required for Some Codes
Codes 175 and 178 (internal board faults) and full system communication resets often require Carrier dealer software and credentials. If you’ve exhausted basic diagnosis, contact a Carrier Infinity-certified dealer.
Infinity Thermostat Error Screen Navigation
Press and hold MENU on the Infinity touch thermostat. Navigate to System Info → Active Faults or Fault History. This shows all current and recent codes with timestamps — useful for intermittent faults that clear before a tech arrives.