E40 - High-pressure switch tripped, system overcharged, service valves shut, or insufficient airflow

What does E40 mean?

This error indicates the high-pressure switch (B3H or 63H1) has tripped, potentially due to system overcharge, closed service valves, or insufficient airflow over the condenser coil.

• High-pressure switch (B3H or 63H1) activation.
• System is overcharged with refrigerant.
• One or more service valves are shut or partially closed.
• Insufficient airflow over the condenser coil (dirty coils, obstructions, faulty fan).

Click steps to track your progress.

1. 1

   Turn off the main power to the AC system at the circuit breaker.

2. 2

   Inspect the outdoor unit for any debris or obstructions blocking airflow to the condenser coil. Clean if necessary.

3. 3

   Ensure the outdoor fan is operating properly.

4. 4

   Contact a qualified HVAC technician to check refrigerant levels, verify service valve positions, and inspect the high-pressure switch.