Why Is Water Leaking From My AC Unit?

If you type “Why is water leaking…” into Google Search, one of the suggested choices is almost always “Why is water leaking from my AC?”

Many people consult the internet when issues arise with their heating and cooling equipment. Wondering about the cause of water leaks is especially prevalent during the summer months. What many HVAC owners don’t know is that a leaking air conditioner is almost entirely preventable.

Read on if you are looking for information on what causes a leaky AC unit, how to prevent it, and how to fix it if it does occur.

Leaking Air Conditioner: Common Causes and Solutions

Condensation is a natural byproduct of a healthy air conditioning system. Since air conditioning revolves around heating and cooling refrigerant, condensation occurs.

Imagine a cold glass of water on a warm day. Water droplets form on the outside. Similarly, when the refrigerant inside your evaporator coils gets cold, the surrounding warm air hits the cold surface and condenses.

This condensation drips off of the evaporator coils into the drain pan below, where it is supposed to flow through the drain pipe to the outdoors.

Through condensation, your air conditioning system naturally dehumidifies the indoor air. However, it can also lead to iced-over evaporator coils and leaking air conditioning systems.

Clogged condensate drain line

A condensate drain line has the job of draining condensate from the overflow pan into a drain pipe that releases the liquid outdoors. If the condensate line is clogged, it can cause the overflow pan to actually overflow. This is the most common cause of AC leaks.

While newer AC units can sense when there is a clogged condensate line and will shut down on its own, older units will simply overflow with condensate until you notice the problem yourself. If your unit has automatically shut itself off and you suspect an issue with your condensate drain line or overflow pan, call a professional technician to come check it out and make any necessary repairs or replacements.

Solution: Prevent clogged condensate drain lines by regularly pouring a cup vinegar down the condensate drain line every 3-5 months. You can use bleach too, but only in the summer when there is a constant flow of condensate to drain it.

If it’s too late and your condensate drain line is already clogged, contact a professional to clear it. The best way to prevent clogged AC drain lines is by scheduling annual air conditioning maintenance at the very beginning of each cooling season. Your HVAC technician will make sure your drain pan and drain line are clean and clear. If, however, you have the right materials and kno whow, you may be able to clear the condensate drain line yourself.

Damaged overflow pan

If you notice water gathering around your indoor air handler, you either have a clogged condensate drain line or a damaged drain pan. If the condensate drain line isn’t clogged, there may be a crack in the drain pan causing the leak.

  • Check the indoor unit for any signs of overflowing water. If the AC is overflowing, contact your local HVAC specialist.
  • Before opening up the access panel, turn off power to the AC at the breaker box.
  • Remove the access panel and use a flashlight to inspect the drain pan, visible underneath the evaporator coils.

Dirty air filter

A dirty air filter can lead to low airflow and frozen evaporator coils. In order for the evaporator coils to function effectively, there needs to be a sufficient amount of airflow over the coils.

If the refrigerant in the evaporator coils doesn’t have the airflow to absorb the heat from the air, condensate will form on the coils and freeze.

When the frozen condensate thaws, you may notice leaking water. If there is a clean air filter, but you still have frozen evaporator coils, you may have blocked air vents/registers, a broken blower motor, or undercharged refrigerant.

As soon as you notice a frozen air conditioner, turn the unit off and do not turn it back on until the source of the problem has been resolved. Learn why your outdoor heat pump unit may freeze over.

Solution: Replace the air filter. We recommend setting reminders for every 30 days to check the condition of your air filter. Depending on a number of factors, you should change your air filter every 30-90 days. But, never wait more than 90 days to replace your air filter.

Low refrigerant

With low refrigerant, the evaporator coils will probably freeze. As we learned from a dirty air filter, once water freezes and melts there will be a leak. In this case, when the water melts off the coils, the water will overflow the drain pan.

If your air conditioner isn’t working well and you notice noises coming from your unit when it is running, you may have a refrigerant leak.

Solution: Never try to fix refrigerant problems on your own. A professional HVAC technician will evaluate your system and determine any necessary repairs or maintenance. Keep in mind that refrigerant works in a closed, pressurized loop. You won’t be low on refrigerant unless you have a leak somewhere. Your HVAC technician should always repair the leak before adding more refrigerant.

Poor insulation leads to condensation

Moisture around air vents and ductwork could be the result of poorly insulated ducts. Condensation is always something to look out for because it can cause leaks when it builds up in the air conditioning system.

Again, think of a cold glass of water on a hot day. When warm air contacts the cold ducts, water can form and cause damage to ceilings and walls.

If you notice wet spots around any of your air vents, you may not have enough insulation. The most common reasons why you may see condensation and moisture around your AC vents are poorly insulated vent boots and not enough insulation in the ducts themselves.

Solution: Consult a professional technician who can inspect and identify any issues with the ductwork or insulation.

Service Champions is known for trustworthy, on-time home service throughout the East Bay, South Bay, and Sacramento areas.

For more information on taking care of your HVAC system this summer, don’t hesitate to contact us.

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