Error E40 / Outdoor Red LED Flashes Once — High-pressure switch tripped

What does E40 / Outdoor Red LED 1 flash mean?

Error E40, signaled by one flash of the outdoor unit's red LED, means the high-pressure switch (63H or 63H1) has tripped. This can be due to system overcharging with refrigerant, a shut service valve, or insufficient airflow over the condenser coil.

• The high-pressure switch (63H or 63H1) has tripped
• System overcharged with refrigerant
• One (or more) of the service valves is shut
• Insufficient airflow (or no airflow) over the condenser coil

Click steps to track your progress.

1. 1

   Turn off the air conditioner's main power immediately.

2. 2

   Check around the outdoor unit for any obstructions blocking airflow to the condenser coil and clear them.

3. 3

   Ensure the condenser coil is clean and free of dirt and debris.

4. 4

   Verify that all service valves are in the open position. This should ideally be checked by a professional.

5. 5

   Contact a qualified technician to check refrigerant levels and inspect the high-pressure switch and valves.