What Causes An AC Drip Pan To Overflow?

What causes an AC drip pan to overflow?

what causes an ac drip pan to overflow

The most common reason for an AC drip pan to overflow is that the drain line is clogged. The drain line is the pipe that carries the condensation that’s collected over time a water from the drip pan to the outside of your home.

If the drain line is clogged, the water has nowhere to go and will eventually overflow the drip pan. It’s actually not uncommon for this to happen especially for air conditioners and HVAC units located at least partially outside.

Is Standing Water in an AC Drip Pan Bad?

When water collects in the drip pan of an air conditioner it can create several problems:

  • Standing water can be a breeding ground for bacteria and mold, spreading throughout the unit that causes health problems for anyone nearby.
  • The water can rust and damage the pan, leading to leaks. Water can damage the floor around the unit if the pan overflows which can mean not only permanent damage to wood or other materials but also mold or mildew.
  • Mosquitoes can breed in standing water if they have access enough to put larvae in the water.

Long story short, yes standing water in an AC drip pan can be bad!

How much water is normal in an AC drip pan?

The amount of water in an AC drip pan will depend on the humidity levels in the environment, the size and capacity of the AC unit, and the amount of use the unit gets.

However, as a general rule of thumb, it’s normal for an AC drip pan to have a few inches of water. This water helps to keep the AC unit cool and prevents it from overworking itself. It’s not normal, however, for the drip pan to be completely full or overflowing. That means there’s likely a clog.

How do you unclog an AC drain pan?

how do you unclog an ac drain pan

You can try to unclog an AC drain with a plunger. Put the plunger over the drain and pull and push the plunger up and down. If the clog doesn’t go away you can try to use a wire hanger.

Straighten the hanger and put it into the drain. Pull and push the hanger up and down to loosen the clog. If neither of these methods works you may want to call a plumber or a handyman to clear it.

The majority of the time, though, it shouldn’t be a problem to fix it yourself.

Will bleach clear a clogged AC drain?

While bleach may be a potent cleaning agent it’s not effective at clearing clogged AC drains. The active ingredients in bleach are designed to break down organic matter, not dissolve mineral deposits. 

As a result, bleach will not be able to break down the build-up of sediment that causes your drain to clog.

In fact, using bleach to try and clear a clogged AC drain can worsen the problem as it can cause the sediment to harden and become even harder to remove.

How does your air conditioning work and why does it collect water?

how does your air conditioning work and why does it collect water

An air conditioner uses refrigerant (freon or another type) circulated under pressure through hoses and piping via a compressor that creates pressure just like a pump. 

As the refrigerant moves through your air conditioner it absorbs heat from the air inside your home to make it cooler and remove some moisture, in the form of water that collects, from the air. The hot air is released outside via an electric fan and the condenser.

Water that condenses from the warm air due to cooling drips into a pan below your air conditioner and is drained outside. It’s normal to see water dripping from your air conditioner since it’s just the water that has been removed from the air inside your home when it’s made colder.

If the air inside your home is very humid there will be more water for your air conditioner to remove. That’s especially true for more humid environments.

If your air conditioner isn’t sized correctly for your home it may not be able to remove all the moisture from the air which can lead to water build-up. If you notice that your air conditioner is collecting a lot of water, or if the water is not draining well, you should contact a qualified HVAC technician to find out what’s causing it.

How much does it cost to unclog an AC drain line?

how much does it cost to unclog an ac drain line

The cost to unblock an AC drain line basically depends on the severity of the blockage and how hard it is to access the drain line. On average expect around $75 to $250. If more parts need replacement it can easily cost twice that or even more but that’s less common.

A simple clog may only require a plunger to clear while a more severe blockage may need to be removed with a drain snake and the drain tube or pipe may even need replacement. 

The most difficult (and expensive) blockages may require a professional plumber’s assistance which involves the use of a chemical drain cleaner and some specially tools for unclogging pipes.

James Marshall
About the author

James is a business management professional and consultant with a former background in maintenance, repair, and hands-on projects. He enjoys DIY tasks and maintenance around the home as well as part-time writing. Read more »