What Is Air Conditioner Drain Slime and How Can You Get Rid of It?

Have you noticed a gooey mess coming out of your air conditioner? It’s likely a substance known as air conditioner drain slime or white slime. If you find white slime in your air conditioner drain line or drain pan, you’ll want to get rid of it quickly before it damages your HVAC system. Here’s how to do it.

What Is the White Slime in My Air Conditioner Drain?

Air conditioner slime is a gooey substance that forms in damp parts of your AC, including the condensate drain line and drain pan. Its purpose is to protect the bacteria within your air conditioner, which thrive in moist and dark environments—like your AC’s drain line.

White slime often shows up in the summer when there’s condensation in your air conditioner. If you don’t get rid of slime in your air conditioner drain, it can cause a number of problems, including a clogged condensate line, overflowing drain pan, restricted airflow, and mold in your air conditioner.

Getting Rid of AC Slime

Unfortunately, wiping away the slime or emptying the water in your drain pan isn’t enough to keep it from returning. Instead, you’ll need to deep clean your AC or hire a local air conditioning repair company to do it for you. Either way, the process will involve: 

• Replacing the air filter

• Vacuuming the AC unit with a wet/dry vac to remove all slime, dirt, and debris

• Flushing out the drain line with a cleaning solution (often vinegar and water)

• Rinsing the drain pan

• Cleaning the evaporator coil

How to Prevent White Slime

Staying on top of your HVAC maintenance is the best way to keep slime from building up in your air conditioner. At a minimum, this involves replacing dirty air filters, cleaning your evaporator and condenser coils, and vacuuming inside your vents.

You should also have a professional inspect your air conditioner every year. During this AC service appointment, the technician will make sure everything is running efficiently and look for any potential problems.

With that said, if there’s anything wrong with your air conditioner (for example, your AC is freezing up), don’t wait until the annual servicing to address it. Otherwise, what should be a minor issue might escalate into a more expensive problem.