Thank Your Plumbers — For Real!

Thank Your Plumbers — For Real!

Refrigerant Restrictions Vs. Leaks — What's The Difference?

by Bill Turner

Refrigerant problems are a common reason for air conditioning service calls. Your refrigerant keeps your system pumping heat away from your home, but it relies on correct pressure levels to do its job. Anything that alters the system pressure can lead to inefficient cooling, operating problems, and even premature wear on costly components.

If your air conditioner is suffering from a problem with its refrigerant lines, it will usually come in one of two forms: leaks or restrictions. This guide will explain why these occur, how they differ, and how to resolve each one with your system.

Why Does Pressure Matter So Much?

Refrigerant pressure can be a surprisingly complex topic, which is why it's best to leave detailed diagnostics and analysis to professional HVAC technicians. However, it's generally true that a lower pressure will result in colder temperatures. If your system pressure falls below specifications, the temperature at your evaporator coil will drop.

Although it might sound nice to have a colder air conditioning system, you don't want your evaporator coil temperature to drop too low. When this happens, the coils can freeze, ultimately preventing the refrigerant from converting into a vapor state. Liquid refrigerant can then travel through the evaporator and reach the compressor, where it can cause significant damage.

What Causes Pressure to Fall Out of Spec?

If your system pressure falls out of specifications, the two most common causes are refrigerant leaks and liquid line restrictions. Leaks can occur almost anywhere in the system, and they'll cause your air conditioner to lose pressure over time. Small leaks may go unnoticed for a while, but they'll eventually reduce the pressure enough to freeze the evaporator coils and create more apparent symptoms.

Liquid line restrictions are another typical reason for system pressure to drop. Although the refrigerant level does not change, the restriction causes pressure to fall on the other side of the clog. Common locations for restrictions include the thermostatic expansion valve (TXV), the filter-drier unit, and the TXV filter screen if your air conditioner has one.

In most cases, the symptoms of a restriction will look relatively similar to those caused by a leak. Since the blockage will reduce pressure at the evaporator, your temperatures will drop, your coils may freeze, and liquid refrigerant may return to the compressor. Any of these issues can potentially damage your system if left unaddressed.

How Can You Know the Difference?

Determining the underlying cause of a pressure drop can be tricky and requires a careful understanding of the refrigerant cycle and expected pressures on both the liquid and vapor sides of the system. If your air conditioner is suffering from low refrigerant pressure symptoms, it's best to rely on an experienced technician to determine whether the underlying cause is a leak or a liquid line restriction.

For more information on AC services, contact a professional near you.


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Thank Your Plumbers — For Real!

When you have a plumber come work on your home, we hope you thank them. Really, you should be thanking any contractor who works on your home, but we are a little partial to plumbers and happen to think they deserve a little more recognition. After all, the stuff inside the pipes they work on doesn't usually smell very good. And even though they wear gloves, they have to get pretty close to it! If you would like to learn a little more about plumbers, then we invite you to read this blog. After learning the basics, you'll really want to thank your plumbers!