Error A4 (10 Green, 4 Red Flashes) — Outdoor unit pressure error

What does A4 mean?

The hydraulic unit's green LED flashes ten times and the red LED flashes four times. This indicates a general pressure fault within the outdoor unit, which could be either too high or too low.

• Low or high refrigerant pressure due to charge issues or blockages.
• Faulty pressure sensor or switch.
• Restricted airflow across the outdoor coil.
• Expansion valve malfunction.

Click steps to track your progress.

1. 1

   Perform a full power reset of the heat pump system by turning off the main breaker for 60 seconds and then turning it back on.

2. 2

   Inspect the outdoor unit for any obstructions blocking airflow and ensure the coil is clean.

3. 3

   Check for any visible signs of refrigerant leaks such as ice buildup or oily residue.

4. 4

   If the error persists, contact a qualified technician, as pressure-related faults require specialized refrigerant handling and diagnostics.