Vehicle air conditioning control systems

1. An air conditioning system of a vehicle having an internal combustion engine, comprising:

an electric compressor;

a condenser that is configured to receive refrigerant output by the electric compressor and that transfers heat from the refrigerant within the condenser to air passing the condenser;

a first control valve;

a first evaporator that is configured to receive refrigerant from the condenser when the first control valve is open and that transfers heat from air passing the first evaporator to the refrigerant within the first evaporator;

a first blower that is configured to blow air across the first evaporator to a first section of a cabin of the vehicle;

a second control valve;

a second evaporator that is configured to receive refrigerant from the condenser when the second control valve is open and that transfers heat from air passing the second evaporator to the refrigerant within the second evaporator;

a second blower that is configured to blow air across the second evaporator to a second section of the cabin of the vehicle; and

a control module that is configured to open the first control valve and start operation of the electric compressor when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator.

2. The air conditioning system of claim 1 wherein the control module is further configured to open the second control valve when the internal combustion engine of the vehicle is on and the second blower is blowing air across the second evaporator.

3. The air conditioning system of claim 1 further comprising an inverter drive configured to apply power to the electric compressor based on a compressor speed command from the control module,

wherein the control module is configured to, when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, set the compressor speed command to a speed greater than zero based on a discharge pressure of the electric compressor.

4. The air conditioning system of claim 3 wherein the control module is configured to:

decrease the compressor speed command as the discharge pressure increases; and

increase the compressor speed command as the discharge pressure decreases.

5. The air conditioning system of claim 3 wherein the control module is configured to determine the compressor speed command based on the discharge pressure until a temperature of the first evaporator is less than a predetermined temperature, and

wherein the predetermined temperature is greater than the freezing point temperature of water.

6. The air conditioning system of claim 1 further comprising an inverter drive configured to apply power to the electric compressor based on a compressor speed command from the control module,

wherein the control module is configured to, when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, set the compressor speed command to a speed greater than zero based on a present power consumption.

7. The air conditioning system of claim 6 wherein the control module is configured to:

decrease the compressor speed command as the power consumption increases; and

increase the compressor speed command as the power consumption decreases.

8. The air conditioning system of claim 6 wherein the control module is configured to determine the compressor speed command based on the power consumption until a temperature of the first evaporator is less than a predetermined temperature, and

wherein the predetermined temperature is greater than the freezing point temperature of water.

9. The air conditioning system of claim 1 further comprising an inverter drive configured to apply power to the electric compressor based on a compressor speed command from the control module,

wherein the control module is configured to, when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, set the compressor speed command to a speed greater than zero based on a discharge pressure of the electric compressor and a present power consumption.

10. The air conditioning system of claim 9 wherein the control module is configured to:

decrease the compressor speed command when at least one of:

the power consumption increases; and

the discharge pressure increases; and

increase the compressor speed command when at least one of:

the power consumption decreases; and

the discharge pressure decreases.

11. An air conditioning control method for a vehicle having an internal combustion engine, comprising:

determining whether the internal combustion engine of the vehicle is on;

determining whether a first blower of the vehicle is blowing air across a first evaporator,

wherein the first evaporator is configured to receive refrigerant from a condenser when a first control valve is open and to transfer heat from air passing the first evaporator to the refrigerant within the first evaporator,

wherein the first blower is configured to blow air across the first evaporator to a first section of a cabin of the vehicle, and

wherein the condenser is configured to receive refrigerant output by an electric compressor and to transfer heat from the refrigerant within the condenser to air passing the condenser; and

when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, opening the first control valve and starting operation of the electric compressor,

wherein a second evaporator is configured to receive refrigerant from the condenser when a second control valve is open and to transfer heat from air passing the second evaporator to the refrigerant within the second evaporator, and

wherein a second blower is configured to blow air across the second evaporator to a second section of the cabin of the vehicle.

12. The air conditioning control method of claim 11 further comprising opening the second control valve when the internal combustion engine of the vehicle is on and the second blower is blowing air across the second evaporator.

13. The air conditioning control method of claim 11 further comprising:

applying power to the electric compressor based on a compressor speed command; and

when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, setting the compressor speed command to a speed greater than zero based on a discharge pressure of the electric compressor.

14. The air conditioning control method of claim 13 further comprising:

decreasing the compressor speed command as the discharge pressure increases; and

increasing the compressor speed command as the discharge pressure decreases.

15. The air conditioning control method of claim 13 further comprising determining the compressor speed command based on the discharge pressure until a temperature of the first evaporator is less than a predetermined temperature,

wherein the predetermined temperature is greater than the freezing point temperature of water.

16. The air conditioning control method of claim 11 further comprising:

by an inverter drive, applying power to the electric compressor based on a compressor speed command; and

when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, setting the compressor speed command to a speed greater than zero based on a present power consumption.

17. The air conditioning control method of claim 16 further comprising:

decreasing the compressor speed command as the power consumption increases; and

increasing the compressor speed command as the power consumption decreases.

18. The air conditioning control method of claim 16 further comprising determining the compressor speed command based on the power consumption until a temperature of the first evaporator is less than a predetermined temperature,

wherein the predetermined temperature is greater than the freezing point temperature of water.

19. The air conditioning control method of claim 11 further comprising:

by an inverter drive, applying power to the electric compressor based on a compressor speed command; and

when the internal combustion engine of the vehicle is on and the first blower is blowing air across the first evaporator, setting the compressor speed command to a speed greater than zero based on a discharge pressure of the electric compressor and a present power consumption.

20. The air conditioning control method of claim 19 further comprising:

decreasing the compressor speed command when at least one of:

the power consumption increases; and

the discharge pressure increases; and

increasing the compressor speed command when at least one of:

the power consumption decreases; and

the discharge pressure decreases.