P121 - Circuit B Low Saturated Suction Temp - Comp B2 Shutdown

What does P121 mean?

Compressor B2 in Circuit B has shut down due to low saturated suction temperature. This is a protective shutdown.

• Low refrigerant charge
• Low airflow
• Dirty coil
• Broken fan belt
• TXV problem

Click steps to track your progress.

1. 1

   Change the air filter if it appears dirty.

2. 2

   Inspect the evaporator coil for dirt or blockages.

3. 3

   Verify the indoor fan is functioning correctly.

4. 4

   A technician will need to assess refrigerant levels and the TXV.