Samsung Air Conditioner Error Code E428

E428 means the Samsung air conditioner has shut down the compressor because the compression ratio, calculated as (high pressure + 1) divided by (low pressure + 1), exceeded 8.5 for more than 10 minutes. This is a protective shutdown designed to prevent compressor damage from sustained pressure imbalance. The root cause is typically a restriction in the refrigerant circuit, a service valve issue, or low refrigerant charge.

No. The E428 error shuts down the compressor specifically to prevent damage, and continuing to force the system to operate could result in compressor failure. Running the unit in this condition risks expensive compressor damage that could make the system unrepairable at a reasonable cost. The system should remain off until the underlying pressure imbalance is diagnosed and corrected.

Repair costs vary widely depending on the cause. If the fix is simply opening a service valve or cleaning a blocked condenser, costs may be limited to a service call fee, typically in the range of $75 to $150. Refrigerant recharge adds roughly $150 to $400 depending on refrigerant type and quantity. Expansion valve or pressure sensor replacement can range from $200 to $600 including parts and labor. Compressor replacement, if damage has already occurred, is typically the most expensive repair and can range from $800 to $2,500 or more.

One check a non-technician can perform is confirming that all service valves on the outdoor unit are fully open, as a partially closed valve is a common and simple cause of this error. Beyond that, diagnosing and correcting refrigerant charge levels, pressure sensor faults, or expansion valve issues requires EPA-certified technicians with proper manifold gauge equipment and refrigerant handling certification. Attempting refrigerant work without the proper tools and certification is unsafe and illegal.

A power reset may temporarily clear the error and allow the unit to restart, but if the underlying cause of the elevated compression ratio has not been addressed, the E428 code will return once the system has run for 10 minutes with the ratio above 8.5. Resetting without diagnosis does not fix the problem and risks repeated compressor shutdowns or eventual compressor damage.