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Subscribe to our RSS Feed Cleaning Evaporator Coils: A Step-by-Step Guide

Friday, June 28, 2013

For many Chicago homeowners, air conditioner maintenance means little more than changing the air filters regularly and cleaning debris from the exterior unit. Proper maintenance also includes cleaning one of the most important parts of your AC: its evaporator coils. When you familiarize yourself with your AC system, cleaning its coils can become a do-it-yourself project that will save you money and extend the life of your air conditioner. DIY AC maintenance can also familiarize you with your system and help you spot strange AC behavior before it becomes a bigger problem.

What Do AC Evaporator Coils Do?

You can easily feel how your AC moves air through your home when you hold your hand to a vent or walk past the filter intake. Another transport system also plays a crucial role, but you won't see it in action. Coolant moves through the equipment in its own closed loop. As it travels through the system, it becomes compressed into a liquid and expanded into a gas in endless cycles. The condenser coils allow gaseous coolant to become a liquid again in your outside unit. Inside, the evaporator coils let liquid coolant transform into a gas, chilling the coils in the process.

Your AC's evaporator coils are where hot air becomes cool. Heat transfer from the warm air to the cold surface of the coils drops the air temperature significantly before fans send the conditioned air into your ductwork and throughout your home. Window units work on the same principle of compression and expansion, but they do so in a smaller space. Both window units and central air conditioners need regular cleaning to function properly. Without it, the evaporator coils build up layers of insulating dust and soil, limiting their ability to absorb heat.

Cleaning Your Air Conditioner's Evaporator Coils

To clean your AC evaporator coils, you will need:

  • Screwdrivers, flat and Phillips head
  • Soft lint brush or whisk broom
  • Commercial coil cleaner designed for indoor use

Before cleaning any part of your air conditioner, shut off all power to the unit. Look for a switch on or near the equipment. After shutting down the system's main power, look for the evaporator coil array. The coils are usually hidden behind an access plate that may or may not be labeled, but you'll recognize them when you see them. You will need a screwdriver to remove the plate and reveal the coils; some systems need a Phillips head screwdriver while others use flat head screws, so bring one of each to limit trips to your attic or basement. If your AC has no visible screws on the sealed plate, you need a professional to service the system.

The copper coils of the evaporator array wind through a series of thin metal fins or vanes. Different systems have different coil configurations, but an A-frame shape is one of the most common. If the coils haven't been cleaned in some time, they may have visible dust build-up that you can sweep away with a soft brush. After removing as much dust as you can with the brush, follow instructions on the spray-on coil cleaner. Double-check before using the cleaner to ensure that it's meant for indoor coils. Cleaners designed for evaporator coils should foam up and dissipate within a few minutes without rinsing.

When the cleaner has done its work, check the drain pan below the coils. The pan catches condensation on the coils and drains it outside your home. Watch how quickly the liquid cleaner drains from the pan; if it seems to be moving slowly or stays in the pan, you may need an HVAC specialist to remove clogs in the drainage system. Replace the front panel when you're sure the coils are clean and the drain pan is working normally.

When to Call a Professional for Air Conditioner Maintenance

DIY AC maintenance is enough to keep your system running efficiently, but sometimes your system needs more help than you can give it. Find a professional HVAC contractor in the Chicago metro area if you see the following:

  • No visible access to coils
  • Overflowing drain pan
  • Ice on the evaporator coil array
  • Damage to coils or fins
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