Mitsubishi is the most popular aircon model in Singapore. It is loved by the user due is many modern features. On of such feature is the ‘protect stop feature’ which will stop the aircon from regular operation. Many Mitsubishi users do not know much about it. Let’s discover what Mitsubishi protect stop feature is, how it works and what to do if you experience this.
What Is Mitsubishi Aircon Protect Stop?
Mitsubishi Aircon Protect Stop is a safety and protection feature found in some Mitsubishi Electric air conditioning units. The purpose of this feature is to protect the aircon system from damage due to electrical issues, system overloads, or abnormal operating conditions.
When the Protect Stop is activated, the aircon will stop working and display an error code. This helps prevent further damage and gives users or technicians a clear sign that something is wrong.
Common Causes of Protect Stop Activation
Below are the common causes for protect mode of Mitsubishi aircon:
Power Surge or Unstable Voltage
Sudden changes in voltage can harm your aircon’s internal parts. Mitsubishi’s Protect Stop feature shuts down the unit to prevent electrical damage.
Dirty Air Filters or Clogged Airflow
If air cannot flow properly, the system overheats. This may trigger the Protect Stop to avoid damage to the compressor and motor.
Gas Leak or Low Refrigerant
When refrigerant levels drop, the aircon cannot cool properly. The system senses the issue and activates Protect Stop for safety.
Faulty Sensors or Wiring Issues
Broken sensors or loose wiring can send wrong signals to the system. To prevent malfunction, Protect Stop will turn off the aircon.
Overheating Due to Poor Ventilation
If the outdoor unit is blocked or the area is too hot, it may overheat. The system will shut down to avoid damaging the compressor.
Poor or Skipped Servicing
Lack of regular maintenance can lead to hidden problems. Protect Stop acts as a warning sign that your unit needs professional attention.
How to Clear Protect Mode to Normal Mode on Mitsubishi Aircon
If your Mitsubishi air conditioner enters Protect Mode (sometimes shown as “Protect Stop”), it means the system has detected a problem. It won’t return to normal until the issue is resolved. Here’s what you can do:
1. Turn Off the Power
Switch off the aircon using the remote control. Then turn off the main power supply to the unit from the electrical switch or circuit breaker.
Wait for at least 5 minutes to allow the system to reset.
2. Turn the Power Back On
Turn on the power supply again and restart the aircon using the remote.
In some cases, this clears temporary issues, and the aircon returns to Normal Mode.
3. Check for Error Codes
If the aircon goes back into Protect Mode, check the error code displayed on the unit or remote control.
These codes help technicians diagnose the issue quickly.
4. Do Not Attempt DIY Repairs
Protect Mode is a safety feature. If the cause is not a simple reset, it means your aircon needs professional servicing.
Trying to fix wiring, gas leaks, or sensor issues yourself can cause more harm.
5. Call an Authorised Mitsubishi Aircon Technician in Singapore
Reach out to Mitsubishi Electric’s official service center or a certified technician in Singapore.
Provide the error code and model number for faster service.
Common Error Codes in Protect Stop Mode
Below are the common error codes during protect stop mode of Mitsubishi aircon.
| Error Code | Meaning | Explanation |
| P8 | Indoor heat exchanger sensor fault | Sensor inside the unit is damaged or disconnected. |
| U4 | Communication failure (indoor ↔ outdoor units) | Wiring issue or control board malfunction causes miscommunication. |
| E6 | Compressor lock / Outdoor fan motor fault | Compressor is stuck or outdoor fan isn’t working properly. |
| P9 | Outdoor unit heat exchanger sensor issue | Sensor gives wrong temperature reading, may cause overheating. |
| L4 | Current overload | Too much current flow—possibly from short circuit or motor issues. |
| F1 | Indoor PCB fault | Indoor circuit board is malfunctioning and needs repair or replacement. |
| U1 | Voltage drop or power issue | Unstable or low voltage detected; unit shuts down for safety. |
| E0 | EEPROM error (memory issue) | Fault in internal memory chip; settings cannot be stored correctly. |
How to Prevent Protect Stop Issues
Prevention is better than cure. Follow these simple steps to avoid Protect Stop problems:
- Clean air filters every 2-4 weeks
- Schedule professional aircon servicing every 3-6 months
- Ensure the aircon is installed in a well-ventilated area
- Use a voltage stabilizer if your area has frequent power fluctuations
- Choose a reliable Mitsubishi aircon service provider in Singapore
Frequently Asked Questions
What does Protect Stop mean on my Mitsubishi aircon?
It means the system has detected a problem and has stopped to prevent damage.
Can I reset the aircon myself?
It’s best not to. Contact a professional to check the issue and avoid further problems.
Is Protect Stop common in Singapore?
It can happen if the aircon is not cleaned regularly or if there’s a power issue.
How do I find Mitsubishi Electric service in Singapore?
Visit the Mitsubishi Electric Singapore website or call their customer support to find an authorised service provider.
