Method for operating an air conditioner in a motor vehicle, and an air conditioner having a refrigerant circuit

An air conditioner for a motor vehicle having a refrigerant circuit which comprises:

• an evaporator having a blower assigned thereto;
• an output-controlled compressor that can be driven by means of an engine;
• a condenser having a blower assigned thereto;
• an expansion device, said evaporator, compressor, condenser and expansion device each being in fluid communication with one another;
• an electronic control device in electronic communication with said refrigeration circuit, said electronic control device being connected to (a) sensors for detecting the state variables selected from the group consisting of high pressure of the refrigerant, speed of a compressor shaft, passenger compartment temperature and outside air temperature, and (b) actuators of output-controlled components;
• a measuring device for measuring the voltage of at least one of the evaporator blower and the condenser blower;
• and
• sensors for detecting the humidity and temperature of the air fed to the evaporator.

An air conditioner for a motor vehicle having a refrigerant circuit which comprises:

• an evaporator having a blower assigned thereto;
• an output-controlled compressor that can be driven by means of an engine;
• a condenser having a blower assigned thereto;
• an expansion device, said evaporator, compressor, condenser and expansion device each being in fluid communication with one another;
• an electronic control device in electronic communication with said refrigeration circuit, said electronic control device being connected to a plurality of sensors for detecting state variables of the air conditioner and to an actuator of at least one output-controlled component;
• a first sensor for detecting the pressure in a control space of the compressor and for generating a first signal representative of said control space pressure;
• a second sensor for detecting the suction pressure in a suction line of the compressor and for generating a second signal representative of said suction line pressure;
• and
• an evaluation circuit arranged downstream of the first and second sensors for producing a differential signal from said first and second signals, and for supplying said differential signal to said electronic control device as a basis for determining whether the compressor is being operated outside its maximum delivery rate.

An air conditioner for a motor vehicle, including a refrigerant circuit comprising:

• an evaporator having a blower assigned thereto;
• a compressor driven by an engine, said compressor being output-controlled;
• a condenser having a blower assigned thereto;
• an expansion device, wherein said evaporator, compressor, condenser and expansion device are in fluid communication with one another;
• an electronic control means, in electronic communication with said refrigerant circuit, for generating, as a function of input signals, output signals for driving actuators for output-controlled components of the air conditioner;
• means for detecting at least two state variables of the refrigerant circuit;
• circuit means for determining a value relating to the current delivery rate of the compressor (V.sub.stroke), said value being derived from the at least two state variables detected by said detecting means;
• and
• circuit means for determining whether the compressor is being operated outside its maximum delivery rate by comparing said determined value with a predetermined value for the maximum delivery rate of the compressor (V.sub.max).