Unit stops cooling, indoor unit may show E4 after some minutes of operation

Safety first: Turn OFF the breaker and wait for the fan to stop completely before working near the blower.

Steps:

• Check airflow: Remove and clean the air filters. Ensure supply and return air are not blocked by curtains, furniture, or covers.
• Inspect fan wheel: Open the front panel and visually inspect the cross‑flow fan (drum). Remove any visible debris (plastic bags, insects, insulation) that may be jamming the fan.
• Spin test: With power OFF, gently rotate the fan wheel by hand. It should spin freely without scraping. If it is stiff or rubbing, check for misaligned housing or bent plastic.
• Check motor wiring: Remove the indoor electrical cover and verify the fan motor connector is firmly plugged into the PCB. Look for burnt marks or melted plastic.
• Test operation: Restore power and run the fan‑only mode. If the fan does not start or E4 returns, the motor or PCB is likely defective.

Note: Replacing the indoor DC fan motor on Hitachi units often requires removing the entire blower assembly. If you are not comfortable disassembling the unit, contact a technician.