Carrier error code P4
What it means
Fan speed fault.
Possible causes
Fan not reaching commanded speed Fan speed feedback circuit failure Mechanical obstruction affecting rotation
Suggested fix
Inspect fan assembly for physical blockage and verify motor and feedback wiring and signals; replace the fan motor or controller if diagnostics show they cannot maintain correct speed.
Safety first. Isolate the power supply before inspecting any unit. Refrigerant-circuit
and electrical repairs must be carried out by a qualified, registered technician.
Other Carrier codes
- E1 — High pressure protection in the refrigeration circuit.
- E2 — Evaporator coil temperature sensor fault.
- E3 — Low pressure protection.
- E4 — Compressor discharge temperature protection.
- E5 — Overcurrent or overload protection.
- E6 — Communication error between indoor and outdoor units.
- EC — Refrigerant leak detection alarm.
- F0 — Low refrigerant protection.
- P0 — High voltage protection.
- P1 — Low voltage protection.