DC heating and cooling systems and methods

A HVAC system for an area of a vehicle to be heated and cooled comprising:

• a condenser;
• an evaporator system comprising a primary coil and a secondary coil, where the evaporator system is arranged to heat or cool the area of the vehicle to be heated and cooled;
• at least one valve;
• a compressor;
• a battery configured to supply power to the compressor;
• a variable accumulator comprising a housing, a piston arranged within the actuator chamber to define an actuator chamber, and an actuator configured to displace the piston relative to the housing;
• and
• a control system comprising a controller operatively connected to the actuator and to at least one sensor;
• wherein
• the variable accumulator is arranged between the evaporator and the compressor;
• a refrigerant fluid flows in a circuit from the condenser, to the evaporator, through the variable accumulator, to the compressor, and back to the condenser;
• the at least one sensor is configured to measure a characteristic of the refrigerant fluid;
• the control system operates based on the characteristic associated with the refrigerant fluid measured by the at least one sensor to cause the at least one valve to allow the evaporator to operate in
• a first configuration in which the refrigerant fluid flows only through the primary coil such that heat transfer from only the primary coil heats or cools the area of the vehicle to be heated and cooled, and
• a second configuration in which the primary coil and the secondary coil are connected to allow the refrigerant fluid flows through both the primary coil and the secondary coil such that heat transfer from both the primary and secondary coils heats or cools the area of the vehicle to be heated and cooled;
• and
• the actuator to displace the piston to vary a volume of the actuator chamber to optimize use of power supplied from the battery to the compressor when the evaporator operates in the first and second configurations.