Indoor unit shows E4 and cooling performance is poor or unit stops after short run

Safety: Turn OFF power before removing covers.

• Step 1 – Check and clean filter: Remove the indoor unit filter and wash with mild soap and water. Let it dry completely and reinstall.
• Step 2 – Inspect indoor fan: With the cover off, verify the blower wheel is clean and spins freely. If the fan does not run when the unit is ON, the fan motor or capacitor may be faulty.
• Step 3 – Clean evaporator coil: If accessible, gently brush or vacuum dust from the coil fins. For heavy buildup, use a foaming coil cleaner rated for evaporator coils.
• Step 4 – Check room airflow: Ensure supply and return air are not blocked by furniture or curtains.
• Step 5 – If E4 persists: Low refrigerant or a faulty thermistor may be the cause. Contact a Carrier technician to check system pressures and sensor readings.