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Reasons Why an Air Conditioning Unit Might Be Leaking Water

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Have you ever imagined how the world would be without air conditioning systems? Unbearable, right? The truth is, HVAC units are an essential part of our lives…they keep away mold and bacteria and, above all, help us live comfortably. When these units are not working properly, they could be a major pain, causing loss of business and quality of life.

Different problems might arise in an air conditioning unit. One of the biggest annoyances could be the issue of leaking water. What are some of the reasons why an HVAC system might be leaking water? How do you fix the problem?

Top Reasons Why an Air Conditioning Unit Might Be Leaking Water

Before we look at the reasons that cause water leakages in HVAC units, it is crucial to understand that some leakages are just fine…they might not indicate a system’s failure! That’s right; some leaks are normal.

If an AC is installed in a very hot or humid area, some tiny droplets might form at the AC from time to time. They are formed due to condensation as the system works hard to keep up with temperature changes. The droplets might go unnoticed and usually dry up. When we talk about ‘water leaking’, we mean some severe leaking – and right there, we have a problem!

Let’s look at some of the reasons an AC would be leaking water.

·      Broken Condenser Pump

For refrigeration to take place, condensation must occur. During the process, drops of condensation are produced, and they drip into a drip pan. When the pan is full, water is siphoned out via a pipe referred to as the condensate line, all thanks to the condenser pump. If the condenser pump is broken, the water will look for a way out, causing the leakage.

To find out if the pump is functioning well, all you need to do is pour some water on the condenser pan and see if the pump drains excess water correctly. If it doesn’t, you’re staring at a malfunctioned condenser pump, and you might need to replace it.

·      Frozen Evaporator Coil

A leaking AC unit might also be an indication of a frozen evaporator coil. Usually, cooling conditioning systems absorb warm air, cool it with the refrigerant, and then release it through ducts and vents. If the airflow is blocked, the moisture absorbed from the air is converted into ice upon reaching the AC coils. When this is the case, the water leakage is usually as a result of the melting ice.

In this case, all you need to do is unblock airflow. The blockage could be due to a cake of dust and debris on the filter. Clean the filter or change it if necessary.

·      Clogged Drain Line

The drain line is usually a PVC pipe that helps move water from an HVAC unit to an exterior point. Over an extended period, sludge might form and, when it does, it attracts mildew and mold growth.

To unclog the drain line, you need to power off the AC unit, then locate the drain line and pour peroxide or distilled white vinegar (you can also use your preferred unclogging agent).

·      Rusted Drip Pan

As you know, water and oxygen create rust. The drip pan is usually exposed to water almost any other time, and over time it might develop some rust – rust causes wear and tear. A drip pan with holes will cause an AC to leak water.

If you meet a rusted/torn pan, all you can do is replace it to rectify the leakage problem. Don’t forget to power off the system before replacing the pan.

Roofing leaks


Not every leak could be caused by the air conditioning unit. Sometimes, the leaks are caused by problems with the roof. Roof installed AC and refrigeration equipment often have water lines, electrical supply, and refrigeration lines transitioning into the main building. These transitions usually go through watertight seals (like Dektite). These seals rely on a perfect installation, plenty of caulking, and of course a well-maintained roof. Any leaks here will cause rain and condensation to leak into the building.

·      Low Refrigerant

An air conditioning unit loses pressure when the refrigerant level is low. Low pressure will consequently cause the system coil to freeze. When the coils begin to melt, they will cause the drip pan to overflow, causing leakage.

Measure the refrigerant charge. If there’s a leak, fix it, then recharge the system. Alternatively, you can replace the refrigerant altogether.

·      Improper Installation

In this day and age, there are many regular customers out there who will try to do almost any repair themselves. With lots of YouTube tutorials at their disposal, some individuals have decided that nothing is impossible. If you find a new HVAC system leaking, the high chances are that it was wrongly installed or improperly sized.

You’re definitely going to spot some red flags, such as an exposed drain pipe, a gap between the condensate tray and the unit, etc. Install the unit properly and see if that fixes the leaking problem.