Common Causes of AC Unit Drip Pan Overflowing With Water

ac-unit-01Have you noticed your AC unit’s drip pan overflowing with water? Most modern-day homes are constructed with the AC compressor on the exterior of the home and the handler/evaporator coils inside (usually the attic). Because some of these parts are located inside the home, it’s important for homeowners to routinely check them for buildups of water. Allowing water to overflow in the drip pan may contribute to mold, mildew and even rot. If you’re still scratching your head trying to figure out what’s causing the AC unit drip pan to overflow, keep reading for some of the most common causes.

Broken Condensate Pump

Small amounts of water in the AC drip pan is perfectly normal. When the warm air passes over the cold coils, it condenses the moisture vapor into water. This water travels down a small pipe where it ends up in the drip pan. In a functional HVAC system, the condensate pump automatically turns on when it comes into contact with water. The water rises in the drip pan and triggers the pump once it reaches a certain point. If the condensate pump is broken or damaged, though, the water will overflow.

The good news is that condensate pumps are relatively inexpensive. You can purchase a brand new one for about $50 bucks, making this a cheap fix. The only downside is that you may need to hire a professional HVAC technician to install it — unless you have experience working on AC units and parts.

Clogged Drain Line

Of course, another possible reason why your drip pan is overflowing with water is because of a clogged drain line. The constant flow of water traveling from the condensate pan down through the drain line may lead to buildups of algae, calcium, and other mineral deposits. Too much of these deposits will restrict the proper flow of water, at which point water will back up and overflow in the drip pan. If you believe this is the reason why your drip pan is overflowing, try flushing it out with a pipe-cleaning solution.

Overflowing drip pans are a serious hazard that homeowners need to be aware of. The excess water can saturate your home’s ceiling, causing rot and mold. What’s even more alarming is the fact that most homeowners fail to realize there’s a problem with their drip pan until the attic is saturated with water. Try to get into the habit of inspecting your attic on a regular basis to look for signs of moisture — including the AC drip pan.

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