Samsung Air Conditioner Error Code E155

E155 is a mixed operation error, meaning the system has detected simultaneous commands to run both heating and cooling modes at the same time. This is not a physically possible operating state for a single refrigerant circuit, so the system faults out to protect itself. It is most common in multi-zone systems where different indoor units are set to different modes.

The E155 error is a protective fault, not a safety hazard in the way that a gas or electrical failure would be. The system shuts itself down rather than operating in a conflicting state, which is the correct response. You should not attempt to bypass or ignore the error, as forcing the unit to run with conflicting mode signals could stress the compressor and refrigerant circuit over time.

Repair costs depend heavily on the root cause. If the fix is simply correcting zone mode settings, there is no parts cost and a service call fee of roughly $75 to $150 may be all you pay. If communication wiring needs repair or replacement, expect $100 to $300 in parts and labor. A main control board replacement, which is the most expensive scenario, typically runs $200 to $600 or more depending on the model and labor rates in your area.

In many cases, yes. Start by checking that all indoor units in your system are set to the same mode, either all cooling or all heating, not a mix of both. If the settings look correct, cut power to the system at the circuit breaker for five to ten minutes and restart. If the error clears and does not return, the cause was likely a temporary communication glitch. If it comes back, a technician should inspect the wiring and control boards.

A power reset, turning the breaker off and back on after several minutes, can clear E155 if the cause was a temporary communication error or corrupted setting. However, if an underlying issue such as conflicting zone settings, damaged wiring, or a faulty control board is present, the error will return after the reset. Always address the root cause rather than relying on repeated resets.