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How Can You Detect a Bad AC Coil?

If your system isn’t functioning as it should, you’re probably noticing ineffective and infrequent cooling, weak or warm air blowing from vents, odd sounds, and leaks around your indoor AC unit.

Leaking, frozen, or rusted evaporator coils are a signal that your coils require some serious help. Buildup of any kind on the exterior of your coils is not normal. But since most homeowners don’t inspect their AC unit very often, these symptoms can easily go unnoticed.

Signs of a Bad AC Coil

Chances are your AC system will show you there's a problem rather than telling you. When your HVAC system is hidden out of sight, it's easy to miss signs of an evaporator coil problem until your unit starts acting up.

Your coils are located inside your air conditioning system. Hidden away, coils can be hard to see and reach. Keep in mind, not all issues call for a coil replacement; dirty coils can leave your unit functioning at half capacity as opposed to stopping it altogether. But if you're not up for a scavenger hunt, keep an eye out for these signs your evaporator coil may be damaged:

Air Conditioner Blowing Warm Air

Your air conditioner isn’t supposed to blow off steam, so if your AC unit is blowing warm air, there’s something wrong. When your evaporator coil fails, it impacts your AC's cooling function.


Noticing more moisture than normal near your indoor AC unit? That can indicate a problem with your AC coils. Signs of a leak can include a puddle near your system, corroded or frozen coils, and an unusual odor coming from your unit.

Weak Air Flow

A broken HVAC coil will slow down the rate at which your system can produce cold air. Leaking or broken coils will cause your unit to produce a weaker air flow, so if you’re noticing the air coming from your system is blowing with less force than usual, it might be time to check your coils for ice forming or dirt buildup.

Next Steps

If anything you've read so far sounds familiar, you're likely dealing with a faulty evaporator coil. Depending on the age of your system, an HVAC professional may suggest either an evaporator coil replacement or recommend purchasing a new HVAC system. Unexpected costs can be daunting, but you'll want to fix the issue both quickly and cost-effectively for the good of your home.

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