Error Code Guide
Carrier Furnace & AC Error Codes
Carrier furnaces generally communicate error codes via a blinking LED light on the control board. You can usually view this light through a small clear window on the lower blower door.
Common Carrier Issues
- Igniter failure
- Flame sensor needing cleaning
- Blocked condensate drain
Diagnostic Error Codes
Limit Circuit Lockout
DIY Fix PossibleThe furnace has overheated multiple times. This is most commonly caused by a severely clogged air filter. Check and replace your filter, then reset the power to the furnace.
Limit Circuit Fault
DIY Fix PossibleThe limit switch is open, meaning the furnace is running too hot. Check your filter and ensure all supply registers in your home are open and unblocked.
Ignition Lockout
Call a ProThe furnace failed to ignite after multiple attempts. This usually points to a failed hot surface igniter or a dirty flame sensor. A technician will need to test the components with a multimeter.
Pressure Switch Did Not Close
Call a ProThe inducer motor is not creating enough draft, or the vent pipe is blocked. In high-efficiency models, this is often caused by a blocked condensate drain or snow blocking the outside PVC exhaust.