Why does my air conditioner smell like mildew
Every summer when I turn on my AC for the first time it smells like wet dog and mildew. I changed the filter last month. I run it for hours and the smell goes away but it comes back every time I turn it off and turn it back on. How do I fix this permanently?
1 Answer(s)
Changing the filter helps but it's not the source of the smell. That mildew smell is coming from your evaporator coils. When your AC runs, moisture collects on the cold coils. Over time, mold and bacteria grow there. The filter catches dust, not mold.
Here's how to fix it permanently. First, turn off the AC and go to your indoor unit. Remove the front panel (usually just clips or screws). You'll see metal fins (the evaporator coils). Spray them with a coil cleaner — you can buy it at Home Depot for $8. Let it sit 15 minutes, then rinse gently with water from a spray bottle. Don't use a pressure washer — you'll bend the fins.
Second, pour a cup of white vinegar into the drain pan (there's a small tube at the bottom of the indoor unit). This kills mold in the drain line, which is the other common source of the smell.
Third, after you clean it, run the AC on "fan only" mode for 30 minutes to dry everything out. Run it on fan mode for 10 minutes after every use to prevent moisture buildup. Do this and the smell will be gone for good.