Signs and Symptoms of a Bad Liquid Line Filter Dryer

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When the air conditioning breaks, there can be a number of different culprits that have caused the cool air to stop flowing, and it will take a skilled technician to diagnose the issues and get the system running again. One of the most common problems that air conditioning systems may face is a plugged or clogged liquid line filter drier, which helps to keep water and dirt out of the compressor. A plugged liquid line filter drier can be the cause of a number of different problems with your air conditioning system.

Restricted Evaporator Coils

One of the problems that can result from a plugged liquid line filter drier is a restricted evaporator coil. The evaporator coil is inside the house sitting above the furnace blower wheel, and if the liquid refrigerant from the liquid line cannot get into or out of the evaporator coil, the coil will be restricted. Pressures may rise and the unit may freeze up, or it may fail to work altogether.

Freezing Evaporator Coil

Restricted evaporator coils may freeze. This comes from a combination of low pressure on the suction or liquid side of the compressor, as well as higher super heat temperatures that can be found by doing a super heat calculation. The temperature across the filter drier will also drop and can be measured using a digital thermometer.

Temperatures Drop Across the Filter Drier

A symptom of a clogged liquid line filter drier is a temperature drop across the filter drier. Filter driers are typically shaped like a hot dog and are about the same diameter. If one end of the filter drier is a markedly higher or lower temperature than the other end, it is likely that the liquid line filter drier is clogged and may need to be replaced in order for the unit to work properly again.

Lower Condenser Coil Temperatures

If the temperature in the condenser coil is lower than normal, it may be because the liquid line filter drier is clogged and is not allowing the liquid refrigerant back into the condenser to open up and cool off. This is another possible symptom of a clogged liquid line filter drier.


Alexis Writing

Alexis Writing has many years of freelance writing experience. She has written for a variety of online destinations, including She holds a Bachelor of Arts in communication from the University of Rochester.