How To Tell If A Liquid Line Filter Drier Is Clogged

Diagnosis 2

The big give abroad was the liquid line temperature right after the liquid line filter/drier. The filter is so clogged that inappreciably whatever refrigerant is getting through. There is such a large force per unit area drop through the filter, it is acting similar a metering device. Liquid refrigerant is flashing to a gas and removing oestrus from the surrounding surface area (the filter drier and information technology's casing). In real life, at that liquid line temperature of 31 °F the filter would exist all frosted upwardly and would certainly stand out like a sore thumb. Withal if the temperature happens to be above 32 °F at that place would be no visible frost, information technology would be sweating instead. This is an example of why it is mutual exercise to place your hands on pipes and "feel" the temperature. A common cold liquid line is not normal. Use common sense and refrain from touching belch lines. They can be hot enough to cause severe burns. Since so little refrigerant is getting through to the evaporator all the other symptoms brand sense.

	The reduced amount of refrigerant getting through the filter/drier can evaporate before traveling very far through the evaporator coil. In that location is therefore a great deal of evaporator area left over for superheating. Hence, there is high superheat.
	The reduced quantity of refrigerant on the low side of the system causes a lower than normal suction pressure level. The compressor keeps trying to remove refrigerant from the evaporator at its normal pumping rate merely the partially clogged filter/drier and the TX Valve cannot keep up with this rate so the low side pressure drops.
	The lower than normal pressure suction vapours enter the compressor. The rarified vapours are compressed yet there are fewer molecules to share the estrus of compression. It's like sharing $100 betwixt 4 people instead of l people. With fewer people, each receives more than coin. With fewer gas molecules each receives more of the rut of compression. This results in higher temperatures. Hence the higher than normal discharge temperature.
	Low pressure vapours are rarified compared to high pressure vapour. Low pressure vapours impose less of a load on the compressor. Since the compressor is performing less work, it draws less amperage. (The compressor motor draws less amperage)
	The hotter than normal discharge gas now enters the condenser. However the partially clogged filter/drier is belongings back the flow. Refrigerant is beingness kept in the condenser for a much longer fourth dimension than normal. Therefore it keeps rejecting heat and cools downwardly more than than normal. The pressure level and temperature drops lower than normal. Hence the lower than normal loftier side pressure level.
	The refrigerant is cooled more than than normal while held back in the condenser by the high side brake. The liquid line temperature therefore decreases and the amount of subcooling increases.

The above explanations should make information technology clear why all the exam measurements varied from "normal" in such specific ways. If you had a tough fourth dimension determining the solutions on the Causes-Effects folio, you should return there now and solve the "Restriction (Liquid Drier)" section. If you empathize the above explanations it should be easy to select the appropriate symptoms. Did you also discover the poor air temperature drop through the evaporator? A mere ii °F temperature drop is not going to provide very effective refrigeration. That explains why the evaporator inlet air is then high. The refrigeration system is running so poorly, the box is gaining heat at a faster charge per unit than the refrigeration system can get rid of it. The air temperature rise through the condenser is also very poor. That'southward because the refrigeration arrangement is running so poorly it is not picking up enough rut to brand a significant heat rejection.
It should not be necessary to make all of the above measurements in order to diagnose a clogged filter/drier. One time it was determined that the system was operating inadequately, checking for a temperature driblet through a filter/drier should be done but to eliminate it equally a possible cause. It takes no fourth dimension at all to experience the inlet and outlet temperatures. If there is no difference you can proceed on your pursuit for the fault. The above prepare of fault related operating parameters is still valuable in demonstrating the inter-relationship of all the operating parameters in the mechanical refrigeration process.