Abstract: A refrigeration cycle apparatus comprises a refrigerant circuit, a water circuit, and a control device. The refrigerant circuit includes a compressor, a four-way valve, a heat exchanger, a fan, a diaphragm mechanism, a water heat exchanger, and an accumulator. Based on a value of a low-pressure sensor or a high-pressure sensor and a water temperature on an outlet side of the water heat exchanger, the refrigeration cycle apparatus determines whether or not there is an abnormality due to dirtiness adhered to a plate inside the water heat exchanger.