Your Car A/C System Cannot Survive Without A Working Evaporator
An evaporator, which is also called an evaporator core, is one of the most important components of the car A/C. This is because it is a heat exchanger, and in most cars or trucks can be found within passenger compartments, beneath an instrument panel. Some automobiles, mostly SUVs or vans, use two evaporators, one which is beneath their instrument panel, and another which is situated in the rear, either within a panel or even the ceiling above passengers sitting in the back.
How Evaporators Are Designed
These contraptions are usually manufactured with aluminum. They are very similar in appearance to radiators, the difference being that they are thicker yet smaller in their overall dimensions. Evaporators utilize a collection of tubes within (also called flow paths) that have fins attached. Air will pass through these tubes freely, transferring refrigerant. When people refer to this refrigerant, they usually call it “Freon,” which is the R-12 refrigerant which was used in most automobile A/C systems until the mid-1990s, after which it was replaced with HFC R-134a.
Regarding heat exchange, within automobile A/C systems low-pressure refrigerant which is liquid will enter an evaporator. The warm air within the vehicle’s interior will then pass through due to a blower fan. Since heat always moves from an area which is warmer to an area which is cooler, the colder refrigerant moving within the evaporator will then absorb heat from the surrounding air. Simultaneously, nearby humidity will condense on the surface of the evaporator, after which it will drip onto the drain tube and then outside the automobile, similar to how moisture appears on a bottle of soda during a hot humid day. This is also the reason you can see liquid dripping beneath some vehicles when their air conditioner is being used. Once the refrigerant is warmer and finishes its path via the evaporator, it must then be transferred to the compressor.
How The Evaporator Functions
The interior of a vehicle is not technically cooled by air conditioning. Rather, the A/C system extracts humidity and warm air from the cabin. The evaporator is similar to the heater core, except it operates in reverse. It is situated within the passenger cabin, usually in close proximity to the dashboard, and it has engine coolant moving through it, which transfers heat from the vehicle’s engine into its interior, where it will be distributed via the blower fan. Since cooler refrigerant moves through the evaporator, it will absorb the heat within the passenger cabin while the blower fan will move warmer air through it.
Why Evaporators Malfunction
Evaporator malfunctions almost always result from leakage, and leaks have many different potential causes. Often, a weld or seam may have deteriorated, which creates a spot that leaks, or corrosion is present. Leaves and other types of organic materials have a habit of getting into the evaporator container via air vents which are located on the exterior. This material creates a moist environment due to its decomposition, which can produce substances which are corrosive and caustic that perforates the evaporator’s surface, while occasionally producing an unpleasant odor within the vehicle itself.