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Why is my air conditioning unit leaking water?

Six reasons why your air conditioner could be leaking water

I would say one of the most common calls our commercial HVAC company in NYC receives on a regular summer day is the my air conditioning unit is leaking water phone call. There are a couple of reasons why an air conditioning unit would be leaking water. Unfortunately so many people don’t realize that 80% of the time, this issue could have been resolved through performing preventive maintenance on the air conditioning unit. Please read the below most common reasons why your air conditioning unit would be leaking water. In future posts I will discuss ways to prevent the units from leaking, and ways to catch the units before they damage any property.

AC Leaking Reason #1

The first reason for your air conditioning unit leaking is that your drain line is backing up and the drain pan is overflowing. Most of the time the drain line gets clogged with dirt and the water has nowhere else to go except back into the pan. The pan can only hold a certain amount of water, so once the pan gets filled it overflows.

During regular preventive maintenance, the air conditioning & heating company is supposed to blow out the drain line, by doing so they are clearing the drain line from any dirt that may be building up. Another way to help reduce the buildup of dirt is to put acid tablets inside the drain pan.

AC Leaking Reason #2

The second reason why air conditioning units can leak water is because the drain line is disconnected. Unfortunately sometimes we will run across installation jobs that were completed poorly, and the PVC fittings were never cemented properly. Its always important to check your drain lines before calling an air conditioning company. If you find that the drain line looks good and secure coming from the unit then it could be one of the other reasons.

AC Leaking Reason #3

The third reason why your air conditioning unit can be leaking water is due to low refrigerant charge. Many times when the air conditioning unit is low on refrigerant it starts to freeze up when running. Once the unit shuts off the ice begins to melt, and water now drips onto the ceiling. If this happens a couple of times, the water can seep through the ceilings and it can become extremely expensive to repair those water damages.

AC Leaking Reason #4

Air conditioning filters can play a big role in an air conditioning water leak. First, is that the dirty filter blocks the air from penetrating through the filter. When the air can’t go through the filter it starts to freeze. As previously discussed, once the ice melts the water then drips.

AC Leaking Reason #5

Another reason for a leaking air conditioning unit could be due to the fact that there was no p-trap and air vent
pvc-ptrap installed in the drain line. The purpose of a p-trap is to allow the water to flow from the unit when the drain is in the negative air flow. If the unit is not trapped properly the unit will then suck air up the drain, filling the pan with water until the water in the pan overflows. The vent is placed after the p-trap to prevent a trap scenario when the line has sags in it. We recommend that if this does happen to you, then you find an emergency plumber such as: to come and help you.

Reason #6

Duct work that was either not insulated, or not insulated properly can condensate and leak water. The reason being, is the temperature difference from hot to cold. The same way an ice cold soda bottle has water on the edges on a hot summer day, so does the air conditioning duct work.

A great solution to these problems that many residential and commercial customers face daily is to start a routine maintenance program. There are several affordable HVAC maintenance contracts in NYC designed to keep commercial customers from experiencing this annoying issue. Plus, residential customers can do many things themselves to reduce air conditioning unit leaking water problems – like simply replacing filters every three months. No matter what option you choose, always take this problem seriously as it could lead to major and often expensive AC repairs.