Indoor unit displays E9 and the unit may shut down or run erratically.

Safety first: Disconnect power before opening the indoor unit control compartment.

• Step 1 – Locate the room sensor:
  • The room sensor is usually near the air intake grille or behind the front panel, often in a small plastic holder.
  • It connects to the indoor PCB via thin wires.
• Step 2 – Check mounting and cleanliness:
  • Ensure the sensor is not hanging loose or buried in dust.
  • Gently clean dust from the sensor with a soft brush.
• Step 3 – Inspect connector:
  • Follow the sensor wires to the PCB and verify the plug is secure.
  • Look for corrosion or broken pins.
• Step 4 – Replace sensor if faulty:
  • If the sensor is physically damaged or tests open/short with a multimeter, replace it with a Hisense-compatible room temperature sensor.
  • Install it back into the original holder so it senses room air correctly.
• Step 5 – PCB check: If a new sensor does not clear E9, the indoor PCB may be defective and should be replaced by a technician.