Error 2135 – Water heat exchanger freeze up detected

What does 2135 mean?

The system detects conditions indicating that the water-source heat exchanger is freezing. This error is critical and requires immediate corrective action to prevent damage to the heat exchanger, refrigerant piping, or surrounding property. A normal power reset will not clear this error in newer versions (Ver 1.24 and later).

• Pump not connected properly or pump failure
• Thermistor fault (TH6, TH8, TH22, TH23) or disconnected thermistor connector
• Shortage of circulating water
• Specific low-temperature detections during operation or defrost cycles

Click steps to track your progress.

1. 1

   Check the pump for proper connection and operation, ensuring it is circulating water correctly.

2. 2

   Inspect thermistors TH6 and TH8, and their connectors for any disconnections or obvious faults.

3. 3

   Ensure there is no shortage of circulating water and the circulating refrigerant amount is correct.

4. 4

   To reset error 2135 (for Ver 1.24 and later): Set DipSW 1-8 of the relevant PWFY-AU unit from OFF to ON, then back to OFF to disable overwrite protection. Then, set DipSW 3-5 on the relevant PWFY-AU unit from OFF to ON. Shut down all power to the refrigerant system (OC, IC, AU, and BU). Set DipSW 3-5 on the relevant PWFY-AU from ON to OFF. Restore power to the entire refrigerant system.

5. 5

   Contact your local Mitsubishi distributor support representative if you have any questions or if the problem reoccurs, as failure to comply may void warranty coverage.