Troubleshooting Guide
Common Mitsubishi Electric AC Problems & Solutions in India
Understanding early warning signs helps avoid costly compressor failures and high electricity bills.
AC Not Cooling or Blowing Room-Temperature Air
When your AC runs but fails to cool the room, dirty filters, outdoor fan failure, or low refrigerant gas are common causes.
- Possible Cause: Dust-choked air filters or blocked indoor evaporator fins
- Possible Cause: Weak outdoor compressor capacitor or fan motor cut-off
- Possible Cause: Refrigerant micro-leakage in copper capillary circuits
- What to Check: Clean air filters and check if the outdoor unit fan is spinning.
- What to Check: Feel if air from the outdoor unit is warm (normal) or room temperature (compressor off).
- What to Check: Professional diagnosis with manifold gauges is needed to verify refrigerant pressure.
Inspection required for exact diagnosis
Book Cooling Check →
Indoor Unit Water Leakage & Dripping
Water dripping from the indoor unit onto walls or furniture usually signals a blocked drainpipe or uneven unit slope.
- Possible Cause: Algae, dust, or mold sludge blocking the condensate drainpipe
- Possible Cause: Improper indoor unit slope or loose drain hose connection
- Possible Cause: Ice buildup on evaporator coils melting rapidly into the tray
- What to Check: Inspect the outdoor drain hose outlet to see if water is trickling freely.
- What to Check: Check if the indoor cooling fins have visible ice frost.
- What to Check: Technician visit is recommended for pressure clearing and drain tray treatment.
Inspection required for exact diagnosis
Book Leak Repair →
AC Not Turning On or Sudden Power Tripping
If the AC display stays blank or trips the MCB breaker immediately upon starting, electrical protection has triggered.
- Possible Cause: Blown power PCB micro-fuse or varistor damaged by voltage surges
- Possible Cause: Short-circuited compressor motor winding or earth leakage
- Possible Cause: Burnt terminal connections or loose isolator wiring
- What to Check: Check if the wall socket switch and MCB are in the ON position.
- What to Check: Do not repeatedly reset a tripping breaker, as this can worsen electrical damage.
- What to Check: A qualified technician must test circuit resistance and repair board components.
Inspection required for exact diagnosis
Book Electrical Check →
Unusual Grinding, Rattling or Buzzing Noise
Abnormal sounds indicate mechanical friction, loose casing screws, or failing blower motor bearings.
- Possible Cause: Cracked or unbalanced cylindrical cross-flow blower wheel
- Possible Cause: Worn ball bearings in the indoor blower or outdoor condenser fan motor
- Possible Cause: Loose outer casing screws or vibration against wall brackets
- What to Check: Identify whether the sound comes from the indoor or outdoor unit.
- What to Check: Check if pressing the plastic front panel gently alters the rattling sound.
- What to Check: Turn off the AC if you hear metal-on-metal grinding to prevent motor burnout.
Inspection required for exact diagnosis
Book Noise Inspection →
Indoor Coil Freezing & Ice Accumulation
Ice forming on the copper coils or blowing out as frost droplets indicates restricted airflow or low gas pressure.
- Possible Cause: Severely choked air filters blocking warm room air circulation
- Possible Cause: Low refrigerant charge causing evaporator temperature to drop below 0°C
- Possible Cause: Faulty indoor temperature sensor misreading return air temperature
- What to Check: Turn off cooling and run fan-only mode to let the ice melt safely.
- What to Check: Clean air filters thoroughly and check for visible oily stains near copper joints.
- What to Check: Call a technician to test running pressure and repair any refrigerant micro-leak.
Inspection required for exact diagnosis
Book Coil Inspection →
Foul Odour or Stale Air When AC Starts
Musty or sour smells coming from the AC vents indicate bacterial growth, mold spores, or stagnant drain water.
- Possible Cause: Bacterial biofilm and fungal mildew inside the moist evaporator coil
- Possible Cause: Stagnant water sitting in a clogged drain pan trough
- Possible Cause: Accumulation of cooking oil residue or pet hair on blower blades
- What to Check: Wash removable air filters and spray mild disinfectant if accessible.
- What to Check: Avoid using heavy chemical room sprays directly into the return air intake.
- What to Check: Deep jet pump cleaning with anti-bacterial foam wash eliminates trapped odour.
Inspection required for exact diagnosis
Book Jet Servicing →