Make sure to check your AC Drain Pan to keep your Air Conditioner working.

14 Sep, 2021

Did you know one of the most important parts of your AC is the condensate drain pan? 

It might seem a stretch to claim this of a simple pan that collects water, but this seemingly insignificant component can even cause your air conditioner to turn off when it is full. 

Condensation is a key part of the air conditioning process, and the AC drain pan is responsible for collecting the resulting water. 

Thus, ensuring this water is safely and efficiently drained is important to the maintenance and cleaning of your unit. 

Here’s everything you need to know about your maintenance and cleaning of your HVAC drain pan.

What is an AC Drain Pan? 

Also known as a condensate drain pan or an AC drip pan, this component of the central air system is responsible for collecting the water droplets that result from the air cooling process. 

Where does this water come from? 

When the air conditioner is set to cool, the evaporator coils fill with compressed refrigerant, dropping their temperatures to almost freezing cold. Warm air drawn in through the air ducts is then passed over the evaporator coils to cool it before it is released back into the room. 

In the same way water droplets occur on the exterior of a cold bottle that has been pulled out of the fridge, the above process causes condensation to happen. 

The water droplets form and collect on the coils and drip into the air conditioner condensation pan

The air conditioner overflow pan protects both the unit and your home from water damage. It also prevents bacteria growth by ensuring the water does not sit—it is instead emptied through a condensate line. 

Where is the Condensate Pan? 

An AC unit typically has two different drain pans: The primary air conditioner drain pan located underneath the indoor evaporator coils and the auxiliary or back up drain pan. 

The primary condensate pan is usually welded to the evaporator coil, making it harder to replace. Steps for how to access condensate drain pan may also be tricky in this case. 

Back up Drain Pan 

The back up drain pan, or the AC overflow pan, can be found below the primary pan inside the unit or under the unit on the exterior. It’s often easier to replace the exterior auxiliary pans because of the ease of access. 

Common Problems With the Drain Pan 

Over time, the AC drain pan can develop problems that affect your unit’s cooling system and efficiency—and, as mentioned before, even stop it from working altogether. That’s why regular professional maintenance is important. 

The most common problems seen with AC drain pans are: 

Cracked or Corroded Pans 

Plastic drain pans may crack over time due to temperature changes, while metal pans—though hardly used in modern units—may rust or corrode and leak at the rust spots. Improper installation may also be a cause of cracking. 

If you notice unexplained pooling of water in the indoor component of the unit or on the floor, it’s likely that your AC condensation pan is leaking. These cracks can be successfully sealed with waterproof sealant depending on their size. 

However, it’s always best to have a professional look at it to determine whether a replacement is needed. 

Clogged Drain Lines

The most common cause of pooling water in the AC drain pan is clogging. 

In addition to water, dirt and debris also collect on the evaporator coils when condensation takes place. This dirt can accumulate over time if it drips off into the drain pan, clogging the drain pipe. 

The clogging is likely to result in an overflowing drain pan, which will trigger an automatic shut-off in some HVAC models. 

However, this is not the worst that can happen: Clogged drain pans are a favorable breeding ground for algae and mold. So while it may seem like a fairly easy fix, it’s always best to contact a technician to drain the line, disinfect it, and place time-release biocide tablets to inhibit any more growth until the next service. 

How to Inspect the Drain Pan and Drain Line 

As we’ve mentioned, a clogged or leaky AC drain pan is bad news—for both your unit and your health. 

Regular inspection of the line ensures you catch any issues quickly. 

Here’s how to do it: 

Inspecting the Condensate Pan 

To inspect your unit’s drain pan, you will need:  

  • A flashlight
  • About a gallon of water 


  1. Turn on the AC at the thermostat and let it run for about 30 minutes. 
  2. Look for any pools of water around the unit and in the indoor air handler. 
  3. Turn off the air conditioner, and turn off power to the unit at the main switch. 
  4. Remove the access panel. 
  5. Inspect the drain pan with your flashlight, checking the condition of your drain pan for any cracks and holes, debris, or obvious clogging. Condensate in the overflow pan is likely an indication of clogging in your drain line. 
  6. Pour the water into the overflow pan slowly. Look out for any leaks as you observe the water level in the pan. It should drain freely into the drain line. 

Inspecting the Line 

Where is my ac drain line? 

Your drain pipe is the one coming from your air conditioner and leading outdoors. 


  1. Inspect the entire line closely for any cracks, holes, or damage. 
  2. Find the cleanout tee, a small vertical section of the pipe, and unscrew its cap. 
  3. Slowly pour water into the line using a funnel. Smooth flow and zero leaks mean a clear, unclogged pipe. 

You can clean your air conditioner yourself if you notice dirt and debris in your unit. However, clogging, line fixes, and replacements are best done by your HVAC technician. 

Call the AC Experts 

The best way to keep your AC unit in tip-top shape is to schedule regular maintenance—yearly, at the beginning of the hotter months is recommended. 

Call our expert HVAC technicians at Valley Service to inspect, clean, or fix your condensate drain line issues today.