Why isn't my mini split going into heat mode?

When a ductless mini-split system refuses to switch into heating mode, the issue is typically caused by incorrect remote control settings, sensor errors, or a stuck reversing valve. First, check your wireless remote to ensure the operating mode is set strictly to "Heat" and that the temperature setpoint is raised at least five degrees above current room temperature. Second, if outdoor ambient temperatures are extremely low—such as below negative fifteen degrees Celsius—some older heat pump models lose efficiency and struggle to engage. Third, an internal communication error or faulty reversing valve solenoid can prevent mode switching. You can troubleshoot by performing a hard electrical reset. You can verify that the mode failure is resolved when clearing error codes or resetting power restores normal heating operation.