Too Low Superheat Due to Low Discharge Temperature

What does U7 mean?

The system continuously detects discharge superheat less than or equal to -15°C [5°F] for 3 minutes, even with the linear expansion valve (LEV) at its minimum open pulse and the compressor running for 10 minutes. This indicates potential liquid floodback to the compressor, posing a significant risk of compressor damage.

• Insufficient refrigerant charge.
• Low discharge temperature leading to poor heat transfer.
• Superheat setting too low for operating conditions.
• Faulty discharge temperature sensor (e.g., P30).
• Low suction pressure contributing to low discharge temperature.

Click steps to track your progress.

1. 1

   Check the installation conditions and ensure a secure connection of the discharge temperature thermistor (TH4).

2. 2

   Inspect the holder of the discharge temperature thermistor for any defects or improper seating that could affect temperature sensing.

3. 3

   Check the coil of the linear expansion valve for disconnection or loose connections.

4. 4

   Check the connection and contact of the LEV-A and LEV-B connectors on the outdoor controller circuit board.

5. 5

   Check the linear expansion valve for proper operation, referring to section 10-6 for diagnostic procedures.