Solving Common A/C Condensate Drain Problems

Several common problems can occur in condensate drains, impairing their proper function. Most commonly, an A/C drain problem will result in mold growth and water damage in the home.

If you see water leaking or moisture around the A/C unit, this is an indication of drainage problems.

STOPPAGE OR CLOGS

WHAT ARE CLOGS? –

Clogs occur as dirt and debris collect on the A/C coils, which are often visible just beneath the outer part of your A/C unit. A/C coils are essentially where the cool air comes from. It is the box of coils lining the outside of the unit, otherwise known as the air handler.

Condensation forms as the unit turns warm air into cool air. This built-up debris then mixes with the water that drips from those coils. A drainage system is in place to move the condensation collected away from the unit. However, when the water mixes with the debris it can create blockages in the condensate drain or cause an obstruction of the evaporator coil.

This creates slow water flow and can cause water to back up into the drain pan and overflow. If the stoppage occurs within the drain line it will also catch the drain pan to overflow.

On the other hand, if debris builds up on evaporator coils the moisture can be redirected to not drain into the fin surface and drain pan. This moisture will drip straight off the surface of the evaporator coil and saturate the insulated platform box.

In situations where the coils are located within the interior of your home, if the collection pan overflows it could result in water damage or mold growth.

HOW DO YOU KNOW THERE’S A CLOG IN YOUR SYSTEM? –

Besides water leakage, your A/C consistently shutting down on its own could be another sign of a blockage. Your HVAC system may shut the A/C unit down entirely if the inline safety float switch is triggered. These overflow units are in place to keep the unit from further damage. This trigger is also called a wet switch.

CAN YOU FIX IT YOURSELF? –

Possibly.

FOLLOW THESE STEPS TO FIX A CLOG IN YOUR A/C COILS –

1. Turn off A/C unit power, then check the tubing for holes or leaks. Pieces will need to be replaced if you find any leaks.
2. Use a shop vac to suck up all water from the drain pan and dispose of it. Then clear the drain of obstructions and sludge.
3. Remove the PVC cap from the drainpipe and remove the clog with a wire brush.
4. At this point, you can pour in a solution that is one part bleach and one part water to clear away all buildup within the pipe.
5. After replacing the PVC cap, turn the A/C unit on.

If problems persist or worsen contact a professional to assess the situation.

HOW URGENT IS THIS PROBLEM? –

Moderate to High

HOW DO I KEEP THIS FROM HAPPENING IN THE FUTURE? –

Schedule a Maintenance Visit

MOLD AND ALGAE

WHAT IS ALGAE BUILDUP? –

The A/C condensate drain and pan are constantly damp, creating conditions that are ripe for the development of mold and algae. As these organisms develop, they can contaminate your indoor air, which can lead to health problems. They can also damage your A/C equipment and contribute to condensate drain clogs.

HOW DO YOU KNOW THERE’S MOLD IN YOUR HVAC SYSTEM? – A musty smell, when your system is running, can indicate there is mold or algae present in your condensate drain. If you suspect mold and algae growth, handle the problem quickly as the presence of bacteria can cause health problems for your family.

CAN YOU FIX IT YOURSELF? –

Yes

Follow these steps to remove mold from your A/C condensate drain –

1. Turn off your A/C, remove the cap of your drain.
2. Flush the drain line with either vinegar, bleach, peroxide, or hot soapy water.
3. Wait thirty minutes, then flush the line with water.

HOW URGENT IS THIS PROBLEM? –

High

HOW DO I KEEP THIS FROM HAPPENING IN THE FUTURE? –

A flush out “tee” in the drain line at the proper location can be used to clear the line. Flush the drain line each month to prevent bacteria and algae buildup.

STANDING WATER OR FULL PAN

WHAT IS A FULL PAN? –

A small amount of water is unlikely to be a reason for concern. But in the case of standing water and a continuously full condensate pan, there is likely a problem.
Standing water is commonly caused by the unit, but a full pan could be the fault of a leaky drain line. Keep an eye out for water damage as there doesn’t have to be present water or a full pan for there to be a problem flying just under your radar.

HOW DO I KNOW THERE’S STANDING WATER IN MY HVAC SYSTEM? –

Water gathering around the condensate drain and signs of water damage are key indicators the pan is full.

CAN YOU FIX IT YOURSELF? –

Possibly

How to remove standing water and empty the pan –

1. Turn your A/C unit off.
2. Use a shop vac to remove all water.
3. Make repairs to leaks.
4. Bring in a professional if you are unable to identify the source of the leak or are unable to install any necessary replacement parts.

HOW URGENT IS THIS PROBLEM? –

Moderate to High

HOW DO I KEEP THIS FROM HAPPENING IN THE FUTURE? –

Regular maintenance and inspections of your unit will help you identify worn parts before any extended damage is caused. You can purchase drain pan tablets which will eliminate any algae growth in the drain pan and prevent problems before they start.

P-TRAP ISSUES

WHAT ARE P-TRAPS? –

Condensate drains typically have traps, which are designed to keep air from moving in or out of the air handler without preventing condensate drainage.

The absence of a properly working p-trap could push unfiltered air into your home and cause an overflow of the condensate drain. In some cases, an improperly installed p-trap can pull the condensate up and soak the HVAC components located near the condensate pan. Depending on the type of trap in use, it can be blown dry with every cooling cycle leading to more problems inefficiency.

The best way to resolve these problems is by contacting your HVAC technician to have the condensate drains cleaned and flushed. To prevent further problems, keep your air filters clean to minimize debris in the system, and have your condensate system cleaned and flushed twice a year as part of routine HVAC system maintenance.

HOW DO YOU KNOW THAT TRAPS ARE DRY? –

Dry traps are a result of a pressure incongruence. It can actually result in a not-so-dry ceiling or floor, caused by the offset pressure pushing water into the home.

CAN YOU FIX IT YOURSELF? –

It’s better to bring in an expert.

WHAT’S THE SOLUTION? –

Some professionals might outfit your HVAC system with a new p-trap setup altogether or implement a fluidic control flow device. Fluidic control flow devices use air to direct pressure in the p-trap, versus water that can lead to condensate overflow.

HOW URGENT IS THIS PROBLEM? –

Moderate to High

HOW DO I KEEP THIS FROM HAPPENING IN THE FUTURE? –

Having your p-trap and unit inspected and cleaned properly with a solution and technique administered by professionals is key to keeping your unit running smoothly. Installing a flush out “tee” in the drain line is beneficial for maintaining your p-trap as covered in our section on mold and algae.

CLEAN YOUR DRAIN TO PREVENT A/C CONDENSATE DRAIN PROBLEMS

You should be cleaning your A/C’s drain at least once a year to prevent any buildup or clogs in the system. Cleanings should be more frequent in warmer locations, like Florida, where the A/C is run more often.

You can have a professional help you with cleanings. But if you decide to go the DIY route it is imperative that you make sure the unit is off before you begin working.

Other measures you can take to prevent problems with your A/C condensate drain include:

• Changing air filters regularly to match your inhabitants’ lifestyle (pets, smoking, etc.)
• Using high-quality air filters for better performance and fewer clogs
• Pour bleach into the drain every 3 to 4 months
• Schedule routine maintenance with a certified professional

For more information on proper A/C maintenance, please fill out the contact form below or give us a call. We’ve been keeping Orlando-area homes comfortable since 1969.

Our goal is to help educate our customers in Orlando, Florida and surrounding areas with energy and home comfort issues specific to HVAC systems.