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Air conditioning is the process in which air inside the passenger compartment is cooled, dried, and circulated. Heat transfers from inside to outside the vehicle.

Automotive air conditioning works on the same principles as household refrigerators and air conditioners. Refrigerant in the liquid state changes to a gas and then to the liquid state; this is a phase change. If the change of state of the refrigerant is to take place, there must be heat transfer. These must happen in the correct location:

– A liquid must take in heat to become a gas 

-A vapor must liberate heat to convert to a liquid 

The air from the back of a house air conditioner installed in a window is hot; the AC removes heat from the house. The heat is removed from the passenger compartment of a car in the condenser. The passenger compartment will cool down if you can bail out the heat faster than it comes in.


When moisture from steam condenses on the cool bathroom mirror, a vapor changes to a liquid. This process is called condensation. As vapor condenses, it releases heat. When steam condenses back to water, it releases this heat. Cooling means taking away heat. During evaporation, heat is absorbed. In our example, evaporating water absorbs heat; your car’s AC refrigerant absorbs heat when it evaporates.


The air conditioning system consists of four significant devices: The compressor, the condenser, the evaporator, and a metering device. Refrigerant circulates among these devices. For an air conditioning system to operate, there must be significant differences in pressure within the system. Changing pressure and the refrigerant’s gas or liquid state regulate the cooling cycle’s operation. The air conditioning cycle has four stages:






Inside the car’s interior is a small, radiator-like device called the evaporator. The liquid refrigerant circulates to the evaporator. After leaving the metering device, the liquid refrigerant flows into the evaporator, where heat is absorbed from the passenger compartment. As a result, it changes to a vapor.

When the compressor repressurizes refrigerant, heat is released to the ambient air at the condenser. 

One of the air conditioning systems’ functions includes dehumidifying the air inside the car. Heat is lost when hot, humid air circulates across the evaporator. Moisture in the air condenses on the evaporator fins like on a glass of ice water. A fan blows the cooled, dehumidified air into the passenger compartment.


The compressor pulls the vaporized refrigerant through the suction line from the evaporator. The compressor pressurizes the heated refrigerant, further increasing its temperature. The condenser is more efficient at removing heat because of the higher temperature of the refrigerant when it gets to the condenser. Most compressors are driven by a belt from the engine crankshaft, although many hybrid cars use electrical compressors.


The compressor pumps the refrigerant through the discharge line to the condenser in front of the engine’s radiator. The condenser is a radiator for the refrigerant. Its job is to transfer the heat absorbed in the passenger compartment to the cooler air flowing through it. Cooling the pressurized refrigerant in the condenser causes it to change from a gas to a warm liquid. When compressed, refrigerant becomes thicker and hotter. Heat transfer cannot occur unless the refrigerant is hotter than the ambient air. Elimination of the heat absorbed as the refrigerant was flowing through the evaporator can occur because of this temperature differential.

Your vehicle’s AC unit will not work as it should if the evaporator, condenser, or compressor malfunctions. If your AC blows warm air, bring it in for a checkup. We will quickly ensure these three essential parts of your A/C unit work as they should and recommend a plan to have you on the road in cool comfort.