Vehicle air conditioning device

1. A vehicle air conditioning device comprising:

a compressor that compresses a refrigerant;

a radiator that causes the refrigerant to radiate heat so as to heat air to be supplied to a cabin of a vehicle;

an outdoor heat exchanger that is provided outside the cabin of the vehicle; and

a control device, wherein

the control device is able to perform at least

an air conditioning operation that causes the refrigerant discharged from the compressor to radiate heat in the radiator, decompresses the refrigerant that has radiated heat, and then causes the refrigerant to absorb heat in the outdoor heat exchanger so as to heat the cabin of the vehicle; and

a defrosting operation that causes the refrigerant discharged from the compressor to radiate heat in the outdoor heat exchanger so as to defrost the outdoor heat exchanger, and

the control device determines whether it is possible to perform the defrosting operation on the basis of outside humidity.

2. The vehicle air conditioning device according to claim 1 , wherein in a case where the outside humidity is more than or equal to a predetermined threshold, the control device does not permit the defrosting operation.

3. The vehicle air conditioning device according to claim 2 , wherein the control device changes the threshold to become lower as outside temperature becomes lower.

4. The vehicle air conditioning device according to claim 1 , wherein

the control device calculates an energy quantity Ed necessary to defrost the outdoor heat exchanger on the basis of the outside temperature, and the control device calculates an energy quantity Ea that represents an amount of heat that can be absorbed from external air in the outdoor heat exchanger after the defrosting operation on the basis of the outside temperature and the outside humidity, and

the control device permits the defrosting operation when it is determined that a gain by heat absorption from the external air is obtained as a result of comparing the energy quantities Ed and Ea.

5. The vehicle air conditioning device according to claim 1 , wherein where a residual energy quantity of a battery is less than or equal to a predetermined threshold, the control device does not permit the defrosting operation regardless of the outside humidity.

6. The vehicle air conditioning device according to claim 4 , wherein where the gain by the heat absorption from the external air is expected to be obtained based on weather forecast information, the control device permits the defrosting operation regardless of the outside humidity.

7. The vehicle air conditioning device according to claim 1 , wherein where an outside temperature is expected to increase on the basis of a weather forecast information, the control device does not permit the defrosting operation regardless of the outside humidity.

8. The vehicle air conditioning device according to claim 4 , wherein where the gain by the heat absorption from the external air is expected to be obtained on the basis of navigation information, the control device permits the defrosting operation regardless of the outside humidity.

9. The vehicle air conditioning device according to claim 4 , wherein where the gain by the heat absorption from the external air is expected to be obtained on the basis of a future driving state of a vehicle that is expected based on a driving state history information, the control device permits the defrosting operation regardless of the outside humidity.

10. The vehicle air conditioning device according to claim 1 , wherein the control device forcibly performs the defrosting operation on the basis of a predetermined input operation.