High-Pressure Switch Tripped / System Overcharge / Service Valves Closed / Insufficient Airflow

What does E40 mean?

The high-pressure switch (B3H or 63H1) has tripped. This can be caused by a system overcharged with refrigerant, one or more service valves being shut, or insufficient airflow over the condenser coil, all leading to dangerously high system pressures.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Ensure all liquid line and suction line service valves are fully open.

2. 4

   Inspect the condenser coil for obstructions and verify the outdoor fan operation to ensure sufficient airflow.