Code 18-11 Indoor Coil Freeze Protection — System is preventing ice on indoor coil

What does 18-11 mean?

The equipment is reducing compressor speed to prevent ice from forming on the indoor coil, as indicated by the saturated suction temperature approaching 32°F. This is a protective measure to ensure proper operation.

• Insufficient airflow across the indoor coil.
• Dirty air filter.
• Restrictive ductwork.
• Insufficient refrigerant charge in the system.

Click steps to track your progress.

1. 1

   Check the indoor equipment for excessive static air pressure.

2. 2

   Inspect and replace the air filter if it is dirty.

3. 3

   Ensure ductwork is clear and not restrictive.

4. 4

   Contact a qualified technician to check refrigerant charge levels.