A121 - Circuit B Low Saturated Suction Temperature Alarm

What does A121 mean?

An alarm for low suction temperature in Circuit B has been triggered. The circuit will stop to protect the compressor.

• Low refrigerant charge
• Low airflow over the evaporator coil
• Dirty evaporator coil
• Broken fan belt
• TXV (Thermostatic Expansion Valve) problem

Click steps to track your progress.

1. 1

   Check and replace the air filter if it is dirty.

2. 2

   Ensure the evaporator coil is clean and free of obstructions.

3. 3

   Verify the indoor fan is operating correctly.

4. 4

   A technician should check refrigerant levels and the TXV.