An air conditioner's thermostatic expansion valve serves as a gate that separates the high pressure areas from the low pressure areas of the system. It also helps to regulate the rate at which the air conditioner's refrigerant enters the evaporator coil. This not only helps to prevent liquid slugging, but also serves as a pressure-reducing process that ensures that the pressure in the refrigerant is as low as it should be, something that is necessary for an efficient air conditioning process. However, when this valve malfunctions, it can cause air conditioner icing problems. Here is what you should know about the thermostatic expansion valve and how it affects your air conditioner when it malfunctions.
Malfunctioning thermostatic expansion valve and abnormally low evaporator coil area pressure
There are times when dirt and other debris accumulate on the parts of the thermostatic expansion valve. This dirt may then clog the valve. This reduces the valve's ability to let fluid pass through. The spring of the thermostatic expansion valve can also freeze. This may also reduce the ability of the valve to properly regulate the rate at which the fluid enters into the evaporator coil.
With the capacity of the thermostatic expansion valve compromised, the rate at which the fluid leaves it will be abnormally low. This will cause an extreme pressure drop that will in turn cause the temperature of the liquid refrigerant to plummet to extremely low levels. Extremely cold refrigerant will therefore enter the evaporator coil area.
Extremely cold refrigerant and evaporator coil icing
The cooling process in an air conditioner usually takes place when the liquid refrigerant changes into a gas. And since this process involves the absorption of heat, it usually has a cooling effect on the warm air that passes over the evaporator coils.
With the liquid refrigerant's temperature being extremely low, the amount of heat that it needs to absorb to turn into a gas is usually more than what manufacturers planned for. As a result, the cooling effect that the changing refrigerant has on the evaporator coil area will be extreme. It will be enough to cause the moisture in the passing air to condense, and then force the resulting condensate to freeze. This is what will eventually cause a layer of ice to form over your air conditioner's evaporator coil.
Evaporator coil icing and air conditioner efficiency
Manufacturers usually use copper when making evaporator coils because it is a good conductor of heat. Its use usually facilitates the efficient exchange of heat between the refrigerant and the passing air. However, if an ice layer forms on the surface of the copper coils, it will reduce the efficiency with which this process takes place. This will then reduce the efficiency with which the air conditioner cools air. To cool a given space, the system will then have to work longer and harder.
Replacing the malfunctioning valve is usually enough to prevent this problem and is something that you should definitely consider if you are having frequent coil icing problems in your air conditioning units.Share