Samsung Heat Pump Error Code E156

E156 indicates a communication error between the main outdoor unit and the sub MICOM, or between two outdoor units in a linked system. The error means the control boards cannot exchange operational data, so the system shuts down to prevent unsafe operation. The most common causes are a damaged communication cable, incorrect board settings for K13 or K14, or a power supply voltage problem.

No. When E156 is active, the heat pump will typically not operate because the communication failure prevents the outdoor units from coordinating safely. Attempting to force operation without resolving the underlying fault could result in uncontrolled system behavior or component damage. The system should remain off until the communication fault is diagnosed and corrected.

Repair costs depend on the root cause. If the issue is limited to a wiring repair or a settings correction, technician labor costs may range from roughly 100 to 250 dollars. If a control board or power supply board needs replacement, total costs including parts and labor can range from 300 to 800 dollars or more depending on the specific unit model and part availability. A proper diagnosis is needed before any cost estimate can be made accurately.

Some checks, such as visually inspecting the outdoor communication cable for obvious cuts or damage, are safe for a knowledgeable homeowner to perform. However, checking internal voltages like the 12V and 5V supply rails and verifying or adjusting the K13 and K14 board settings requires access to the outdoor unit control board and should be handled by a qualified HVAC technician. Incorrect adjustments to board settings can cause additional faults.

A power reset may temporarily clear the error code, but E156 will return if the underlying cause has not been fixed. If the communication cable is damaged, the supply voltages are out of range, or the K13 and K14 settings are incorrect, the fault will reappear as soon as the units attempt to re-establish communication. A reset alone is not a repair.