Compressor Overcurrent Interruption

What it means

This code appears on the wired remote of Mitsubishi Electric Mr. Slim ducted, ceiling and cassette units. It means the inverter board shut the compressor down because the current it draws went over the allowed limit while running, unlike U6, which is usually tied to a sudden current spike or the power module. The outdoor unit stops for protection, may retry, and locks out with the code if the trip repeats. The same code can mean something else on other brands, and wall-mounted Mitsubishi Electric models show errors as lamp blinks with a different meaning.

Models covered: Mitsubishi Electric ducted, ceiling and cassette units (Mr. Slim) with check codes on the wired remote; wall-mounted Mitsubishi Electric models may show errors as lamp blinks with a different meaning.

Related codes: U6U1U2U5

Symptoms4

• The outdoor unit stops after running for a while, especially in extreme heat, and UP appears.
• Weak cooling and a hot outdoor unit before the stop.
• Repeated trips after restarting.
• Unusual noise or vibration from the compressor in some cases.

Possible causes6

• High operating pressure from a dirty condenser or weak outdoor fan, increasing compressor load.
• A closed service valve or a restriction in the circuit.
• Refrigerant overcharge or liquid returning to the compressor.
• Low or fluctuating supply voltage.
• A fault in the current sensing circuit or the inverter board.
• Internal compressor wear raising its current draw.

How to diagnose6

1. Turn the unit off at the breaker, let it cool, and do not keep restarting it.
2. Make sure the condenser is clean, the outdoor fan turns and the unit has enough clearance.
3. Switch off at the breaker before opening any panel; the outdoor unit and its inverter board keep a dangerous charge for a while after switch-off.
4. The technician measures supply voltage and compressor current while running and compares them with the manufacturer specification.
5. The technician measures operating pressures and checks the service valves are open and the charge is correct.
6. If conditions are normal and the code persists, the inverter board and compressor are tested.

How to fix6

1. Wash the condenser and repair the outdoor fan if it is weak.
2. Open the service valves or clear the restriction.
3. Have a licensed technician correct the refrigerant charge by weight.
4. Fix the supply problem and fit a voltage protector.
5. Replace the inverter board or compressor at an authorized service center if proven faulty.
6. Run the unit in hot conditions, monitor current and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when washing the condenser or opening a valve fixes it, rises for charge correction or a fan motor, and is highest for an inverter board or compressor.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions