Low Pressure Fault / Low Voltage Detected

What does E49 mean?

The system has detected either a low refrigerant pressure condition or a low voltage condition. Low pressure often indicates insufficient refrigerant charge, while low voltage points to power supply issues to the outdoor unit.

• Refrigerant system pressure is too low, potentially due to a leak or low charge.
• Low voltage detected at the system's power input (e.g., below P1-24VDC).
• Operation under conditions that cause abnormally low suction pressure.

Click steps to track your progress.

1. 1

   Measure system low-side pressure using manifold gauges — perform leak detection and recharge if low.

2. 2

   Measure incoming AC line voltage at the outdoor unit's main power terminals — compare to nameplate requirements.

3. 3

   Check for loose power connections at the outdoor unit's main terminal block and internal wiring.