How Do Bent Fins Affect an Air Conditioner?

Bent aluminum fins on an air conditioner coil can reduce the air conditioner's ability to absorb and exchange heat. For this reason, many home improvement stores and heating and cooling outlets sell "fin combs," small tools used to straighten bent air conditioner fins. This, coupled with a thorough cleaning, can improve the efficiency of your unit.

On the cold side of the air conditioner coil, that is, the side that is inside the central air conditioner air handler or on the inner half of the window air conditioner, bent fins can reduce air flow. Bent fins prevent the air being pulled in from the house from being evenly distributed across the cold refrigerant coils. Consequently, portions of the coil may be blocked off and less overall air can be cooled by the unit.

On the hot side of the air conditioner, that is the outdoor half of a window unit or the outside air condenser on a central unit, bent fins inhibit the exchange of heat. Air conditioners work by absorbing heat from the air inside the home and dissipating that heat outside. If the fins on the condenser are bent, air cannot be sufficiently cycled across the hot coils and some heat is retained, reducing the overall efficiency of the unit.

It is imperative that air conditioner coils and fins be kept free from dirt and debris. Bent fins are more difficult to vacuum or wipe down due to the decreased amount of space between each piece of metal. Over time, the bent portions of the coil can become clogged with dirt and debris, thereby further reducing efficiency by inhibiting air flow.

While bent fins do not necessarily indicate a damaged coil, they can make it easier for damage to occur. Aluminum fins, in addition to aiding air flow, act as buffers between the delicate copper coils and the outside world. A piece of outdoor shingle or hail that hits already weakened and damaged fins can more easily pierce the copper coil and lead to a refrigerant leak. Bent fins should be straightened using a plastic "fin comb," which can be purchased at home improvement stores.