High-Pressure Switch Trip

What does E40 mean?

The high-pressure switch (B3H or 63H1) has tripped. Common causes include system overcharge, one or more service valves being shut, or insufficient airflow over the condenser coil, all leading to excessively high head pressure.

• High-pressure switch has tripped due to excessive system pressure.
• Refrigerant overcharge in the system.
• Poor heat transfer in the outdoor unit coil.
• Obstruction in the refrigerant flow path.
• Faulty high-pressure switch.

Click steps to track your progress.

1. 1

   Measure system high-side pressure using manifold gauges.

2. 2

   Check refrigerant charge using manifold gauges and subcooling calculations — evacuate and recharge with the precise amount if overcharged.

3. 3

   Inspect all service valves in the liquid and suction lines — verify they are fully open.

4. 4

   Verify condenser coil cleanliness and unrestricted airflow; check outdoor fan motor operation and fan blade integrity.