Ductless heat pumps are remarkably quiet during operation. People constantly tell us they’re surprised how quiet the system is – sometimes even checking to make sure the unit is turned on. But a ductless heat pump can make noises. In addition to the low-level fan sound (both indoor and outdoor units), you may hear “whirring”, “clicking”, or “rushing fluid.” These sounds can be the result of thermal expansion, refrigerant movement, or mechanical parts. This is normal. If you encounter any of these sounds, please refer to the owner’s manual for indications. If the indications are for abnormal operation or if you become concerned, call us and we will be happy to check it out.