Understanding The Difference Between High And Low Side AC Leaks

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How to Keep Your Cool When the Mercury is Rising

When the heat is rising to record-breaking levels, it can be really tough to stay cool. This summer, I found that my air conditioner had trouble keeping up with the temperatures. It wasn't that the AC wasn't working, it was just that I couldn't seem to get my house cooled down as much as I wanted. I worried that I would have to replace the whole AC system. Luckily, I have a good friend who works as an HVAC contractor. He took a look at my system and gave good news -- it didn't need to be replaced. Instead, he shared a lot of tips for helping my air conditioner work more efficiently, as well as some ideas to help supplement the AC and keep the house cooler. I'm using those tips to create this blog to share ways for all of us to keep cool on the hottest days.

Understanding The Difference Between High And Low Side AC Leaks

19 October 2020
 Categories: , Blog


Refrigerant is the magical substance that allows your air conditioning system to function. Your system's refrigerant absorbs heat from your home and transports it outside, repeating this process many times over on hot and humid summer days. It's not enough to have refrigerant in your lines, however. Your AC system relies on a relatively precise refrigerant pressure to function correctly.

When something disrupts this careful balance, it can place extra strain on expensive components such as the compressor. Leaks are the most common reason for pressure changes, but their behavior can vary based on whether they occur on the low-pressure or high-pressure side of your air conditioning system.

What Are Low Side Leaks?

You can think of the low side of your refrigerant loop as its interior portion. On this side of the system, the refrigerant is a cold, low-pressure liquid. The refrigerant line on the system's low side is often known as the suction line because the compressor's action pulls refrigerant towards it. Leaks on the suction side most commonly occur in the evaporator coil or one of the fittings.

When a low side leak develops, it can potentially contaminate other components in the system. As the refrigerant moves towards the compressor, the suction can pull dirt, dust, and air into the line. Not only will your system's pressure be affected, but damage to your compressor or expansion valve is likely if the leak goes unaddressed for long enough.

What Are High Side Leaks?

Your refrigerant travels along the high side of your system after leaving the compressor and before arriving at the evaporator coils. On the high side, the refrigerant is a hot, high-pressure gas. The compressor's action "pushes" refrigerant on this side of the system through the condenser coils and into your home. Leaks here typically occur in the condenser coils or its fittings.

Unlike low side leaks, leaks on the high side typically do not pull moisture, air, or other contaminants into the system. The pressure differential between the refrigerant and ambient environment means that these leaks will cause a noticeable loss of refrigerant pressure. A severe leak like this will generally cause your air conditioner to freeze and shut down.

How to Address AC Leaks?

Finding and repairing a refrigerant leak is not a job suitable for most do-it-yourselfers. Any sudden change in your air conditioner's performance warrants a call to an HVAC professional for evaluation and diagnosis. Likewise, ice forming on your AC lines can indicate a potential loss of refrigerant pressure. By addressing these issues, you will avoid causing costly damage to other components.

For more information, reach out to a local air conditioning repair service.