Reduction of condensation in vehicle HVAC systems

1. A method of reducing condensation within a heating, ventilating, and air conditioning (HVAC) system in a vehicle, the HVAC system including a compressor, an evaporator, and a blower, the method comprising:

determining whether a power state of the vehicle has been switched from an active state to an inactive state;

responsive to determining that the power state of the vehicle has been switched from the active state to the inactive state, causing a fresh mode air source to be selected for an intake of the blower;

determining whether an ambient temperature is greater than or equal to a predetermined temperature value;

determining whether the compressor was in operation prior to the vehicle having been switched from the active state to the inactive state;

determining whether a temperature of the evaporator of the HVAC system is rising, wherein the determining whether the temperature of the evaporator of the HVAC system is rising includes determining if a rate of change of the temperature of the evaporator is greater than or equal to a predetermined rate of change; and

responsive to determining that the ambient temperature is greater than or equal to the predetermined temperature value, further responsive to determining that the compressor was in operation prior to the vehicle having been switched to the inactive state, further responsive to determining that a battery voltage is above an acceptable battery voltage threshold, and further responsive to determining that the temperature of the evaporator is rising at a predetermined rate of change while the compressor is in an inactive state, causing the blower to be activated such that air from the fresh mode air source is blown across the evaporator, wherein the blower is stopped by a controller if the battery voltage decreases below the acceptable battery voltage threshold.

2. The method of claim 1 , wherein the predetermined temperature value is from 30 degrees Fahrenheit to 50 degrees Fahrenheit.

3. The method of claim 2 , wherein the predetermined temperature value is 32 degrees Fahrenheit.

4. The method of claim 1 , wherein the determining whether the compressor was in operation prior to the vehicle being switched from the active state to the inactive state includes analyzing a flag stored in a data store operatively connected to an HVAC controller, and wherein the flag indicates an operational status of the compressor.

5. The method of claim 1 , wherein the predetermined rate of change is 10 degrees Celsius per 5 minutes.

6. The method of claim 1 , wherein the causing the blower to be activated includes causing the blower to be alternated between active periods and inactive periods for a predetermined duration.

7. The method of claim 6 , wherein each active period is from 20 seconds to 30 seconds.

8. The method of claim 7 , wherein each inactive period is ten minutes.

9. The method of claim 8 , wherein the predetermined duration is 60 minutes.

10. A method of reducing condensation within a heating, ventilating, and air conditioning (HVAC) system in a vehicle that has been switched to an inactive state, the HVAC system including a compressor, an evaporator, and a blower, the method comprising:

causing an intake mode switch to select a fresh mode air source intake for the HVAC system;

determining whether an ambient temperature is greater than or equal to a predetermined temperature value using data acquired from at least one ambient temperature sensor;

determining whether the compressor was in operation prior to the vehicle being switched to the inactive state;

determining whether a temperature of the evaporator is rising, wherein the determining whether the temperature of the evaporator is rising includes determining if a rate of change of the temperature of the evaporator is greater than or equal to a predetermined rate of change; and

responsive to determining that the ambient temperature is greater than or equal to the predetermined temperature value, further responsive to determining that the compressor was in operation prior to the vehicle having been switched to the inactive state, further responsive to determining that a battery voltage is above an acceptable battery voltage threshold, and further responsive to determining that the temperature of the evaporator is rising at a predetermined rate of change while the compressor is in an inactive state, causing the blower to be activated such that air from the fresh mode air source is blown across the evaporator, wherein the blower is stopped by a controller if the battery voltage decreases below the acceptable battery voltage threshold.

11. The method of claim 10 , wherein each active period is from 20 seconds to 30 seconds.

12. The method of claim 11 , wherein each of the inactive periods is ten minutes.

13. The method of claim 12 , wherein the predetermined duration is 60 minutes.

14. A vehicle heating, ventilating, and air conditioning (HVAC) system operable to reduce condensation within the HVAC system after a vehicle is switched from an active state to an inactive state, the system comprising:

a sensor system operable to sense an ambient temperature and to sense an evaporator temperature;

an intake mode switch to select a source of air for an intake for the HVAC system;

a compressor operable to increase a pressure of a refrigerant;

an evaporator;

a blower operable to blow air from the intake across the evaporator; and

a controller operatively connected to the sensor system, the controller being programmed to initiate executable operations comprising:

causing the intake mode switch to select a fresh mode air source;

determining whether the ambient temperature is greater than or equal to a predetermined temperature value;

determining whether the compressor was in operation prior to the vehicle being turned to the off state;

determining whether the evaporator temperature is rising, wherein the determining whether the evaporator temperature is rising includes determining if a rate of change of the temperature of the evaporator is greater than or equal to a predetermined rate of change; and

responsive to determining that the ambient temperature is greater than or equal to the predetermined temperature value, further responsive to determining that the compressor was in operation prior to the vehicle having been switched to the inactive state, further responsive to determining that a battery voltage is above an acceptable battery voltage threshold, and further responsive to determining that the temperature of the evaporator is rising at a predetermined rate of change while the compressor is in an inactive state, causing the blower to be activated such that air is blown across the evaporator, wherein the blower is stopped by the controller if the battery voltage decreases below the acceptable battery voltage threshold.

15. The system of claim 14 , wherein the predetermined temperature value is 32 degrees Fahrenheit.

16. The system of claim 14 , further including one or more data stores operatively connected to the controller, and wherein the determining whether the compressor was in operation prior to the vehicle being switched to the off state includes analyzing a flag stored the one or more data stores.

17. The system of claim 14 , wherein the causing the blower to be activated includes causing the blower to be alternated between active periods and inactive periods for a predetermined duration.

18. The system of claim 17 , wherein each active period is from 20 seconds to 30 seconds.

19. The system of claim 18 , wherein each inactive period is ten minutes and the predetermined duration is 60 minutes.