Samsung Heat Pump Error Code E605

E605 indicates an indoor unit Electronic Expansion Valve open error that has been detected on a second consecutive check cycle. It means the EEV controlling refrigerant flow to one indoor unit is not closing or moving correctly. This can be caused by a wiring fault, a failed valve coil, a stuck valve body, or refrigerant migrating into a stopped indoor unit. The error requires hands-on diagnosis starting with the EEV wiring harness at the indoor PCB.

Continued operation with E605 is not recommended. A stuck-open EEV allows refrigerant to migrate into a stopped indoor unit, and when that unit restarts it can send liquid refrigerant back to the compressor, causing serious mechanical damage. The system should be serviced before extended operation resumes.

A power reset may temporarily clear the fault display, but because E605 is a second-detection error the underlying problem will cause it to return quickly if the valve defect is still present. Resetting without repairing the root cause does not protect the system from compressor damage due to liquid refrigerant migration. The fault should be diagnosed and corrected before relying on the unit for normal operation.

The initial wiring check, confirming the EEV connector is fully seated and free of corrosion, is something a capable DIYer can perform. However, measuring valve coil resistance, diagnosing PCB output signals, and handling refrigerant all require technical tools and, in the case of refrigerant work, EPA Section 608 certification. Most E605 repairs are best handled by a licensed HVAC technician.

Repair costs depend on the root cause. A wiring fix or connector reseating may cost relatively little in labor, roughly $75 to $150 for a service call. Replacing the EEV assembly typically runs $150 to $400 or more depending on the unit and labor rates. If refrigerant recovery, recharge, or PCB replacement is also needed, total costs can climb to $400 to $900 or higher.