One of the most common air conditioning problems is a leaking air conditioner. Left unchecked, these leaks can cause major water damage, seeping into the floor and continuing its path through the ceiling and walls.

If you notice any water, water damage, or moisture around your AC unit, follow these steps to troubleshoot and fix the problem.

6 Reasons Why Your AC Is Leaking

1. Refrigerant Leak

Most likely, the leak is water and not refrigerant, but if you are low on refrigerant, it should be obvious.

Here are some ways you can tell if you are low on refrigerant:

Air conditioner is not cooling or not cooling as fast
Supply vents are blowing warm/room temperature air
Electric bills are higher than normal
Ice around outdoor condenser unit
You can hear a hissing or bubbling sound near the refrigerant line

If you think that you’re low on refrigerant, turn your AC off and contact a professional as soon as possible. The technician will need to repair the leak before recharging the refrigerant.

2. Drain Line Tubing

If you have eliminated leaking refrigerant from your prognosis, the next step is to investigate your condensate drain line system.

Turn power to your air conditioning off at the thermostat and the breaker.
Find your indoor air handler.
Look for white PVC drain tubing near the bottom of the central air conditioner. The central air conditioner is normally mounted above the furnace assembly.
If you notice any leaking from the PVC condensate drain line, contact a professional for repair or replacement.

3. Cracked, Ill-Fitting, or Missing Drain Pan

First, turn off power to the unit from the breaker box.

Locate the drain pan located underneath the evaporator coil assembly in your indoor air handler.
The central air conditioner is normally installed directly above the furnace chamber. The evaporator coils take up most of the space. Directly below the coils should be a condensate drain pan.
Follow the owner’s manual instructions to remove the panel. If you cannot locate it, contact your local HVAC technician.
Use a wet/dry vac to remove any condensate in the pan.
Now use a flashlight to inspect the drain pan for any cracks or damage. While you can seal small cracks with epoxy glue or water sealant, it’s probably best to replace the entire drain pan. Contact a professional to install a new one.

4. Overflowing Drain Pan and Clogged Condensate Drain Line

Your air conditioning system has a condensate drain line to remove condensation that has gathered in the overflow pan.

These drains may get clogged up with mold and debris thus preventing the unit from being able to properly drain the condensate. When that happens, water can back up and leak around your indoor unit. Think discolored carpets, warped floors, and sagging ceilings.

Avoid such problems by opening up the PVC cap to the drainpipe and passing a strong, stiff wire through the drain. This should help get rid of algae, mold, and sediments that cause clogging.

Then, pour a cup of liquid chlorine bleach down the line. A cup of liquid bleach can be poured down the line every 6 months or so. It will help kill algae, mold and mildew in the pipe.

If, however, your condensation line is completely clogged, you will need to call a professional or use a wet/dry vac and an attachment that fits to your drain line.

5. Room/Window Air Conditioner 

If you have a window AC unit, all the same parts are there (condenser, compressor, evaporator coils, fan, etc.) just in a different configuration. The condensate that forms when humid air hits the cold coils collects in little alcoves that are tilted toward the outdoor section.

In some models, the condensate is blown by the fan against the hot condenser coils in the outdoor section. This produces quick evaporation and helps the AC operate more efficiently. So, there’s no reason to be worried if you don’t see water dripping from your window unit.

6. Air Filter

In any air conditioning system, air filters need to be replaced once every month or so to keep the unit clean and efficient. Keep in mind that some air filters need to be cleaned while others should be replaced. Follow the instructions carefully.

Learn more about air filters, MERV ratings, and how to improve indoor air quality.

Schedule Professional AC Maintenance

Schedule a professional air conditioning tune-up in the early spring.
Schedule a professional heating tune-up in the fall.

With the weather heating up, now is the time to make sure your unit is running in tip-top shape. If you haven’t scheduled AC maintenance this year, get it done as soon as possible.

If none of the above tips have solved your problem, you may have a problem with your thermocouple, capacitor, or refrigerant. These repairs will require the expertise of a qualified heating and air conditioning technician.

If your air conditioner is leaking or isn’t working properly and you live in the Birmingham, AL area, contact OnTime Service.


Give OnTime Service a call to schedule your next air conditioning service at 205-942-1405.