There are times when the thermostatic expansion valve becomes faulty or gets clogged with dirt. When this happens, it usually creates conditions that make evaporator coil icing unavoidable. Here is what you should know about why your air conditioner's thermostatic expansion valve is to blame for your evaporator coil icing problems.
Malfunctioning thermostatic expansion valve and coil icing
The refrigerant-regulating role of the thermostatic expansion valve usually involves it letting only as much refrigerant as the evaporator coil can handle to pass through. When this valve gets blocked by dirt or malfunctions, it can end up allowing too little of the refrigerant to get through. And since the air conditioning system is a closed system, the drop in the volume of refrigerant in the evaporator coil will lead to abnormal pressure drops that will then cause an abnormal drop in the evaporator coil temperatures. This extreme temperature drop will then not only reduce the moisture-carrying capacity of the air passing over the coils, but also freeze any of the condensate that forms over the coils. This is what causes evaporator coil icing.
Complications of evaporator coil icing
The icing that occurs as a result of evaporator coil icing has two main effects on an air conditioning system. The first is that it increases the risks of air conditioner water leaks. The second is that it reduces the overall performance of the air conditioner.
Every time moisture freezes, it is stored in the evaporator coil area. If this goes on for some time, the amount of moisture that is essentially "stored" in the evaporator coil area increases. And when this ice melts, it will release all this water at once. This increases the chances of the condensate drainage system getting overwhelmed, increasing the odds of an air conditioner water leak. As for the reduced performance effect of icing, it usually occurs mainly because ice is a poor conductor of heat. Layers of ice forming over the evaporator coil will therefore reduce the effectiveness of the heat exchange process that happens in the area, something that will then reduce the air conditioner's cooling capacity.
To protect your air conditioner from the devastating effects of icing, simply replace its thermostatic expansion valve. Doing so will save you from having to deal with the devastating effects of water damage. And by improving the performance of your system, it will also go a long way towards reducing your energy bills.