Samsung Air Conditioner Error Code E451

E451 indicates that the low pressure switch in the refrigerant circuit has been triggered a second time, signaling a persistent low-pressure condition on the suction side of the system. The unit has detected this fault more than once and has locked out compressor operation to prevent damage. Common causes include a refrigerant leak, a faulty low pressure switch, or a restriction in the refrigerant circuit.

No. The unit's control system has already stopped the compressor as a protective measure, and attempting to override or reset the unit to resume operation without addressing the underlying cause can result in compressor damage. Operating a system with a low refrigerant charge or a blocked circuit puts significant mechanical stress on the compressor.

A power reset may temporarily clear the fault code and allow the unit to restart, but if the underlying pressure problem is still present, the low pressure switch will trip again and E451 will return. Because this is a second-detection fault, the system has already attempted to recover once. Repeated resets without repair can lead to compressor damage and should be avoided.

Some basic checks, such as inspecting the outdoor unit for airflow obstructions or verifying the unit has power, can be done without special tools. However, diagnosing and repairing the root cause typically requires refrigerant handling certification, manifold gauges, and electrical testing equipment. Refrigerant work must be performed by a certified HVAC technician in most regions.

Repair costs vary depending on the root cause. Replacing a low pressure switch is generally a lower-cost repair, typically in the range of $100 to $250 including labor. If a refrigerant leak is involved, costs can range from $200 to $600 or more depending on the leak location, the amount of refrigerant required, and regional labor rates. A compressor replacement, if the unit ran unprotected for an extended period, would be significantly more expensive.