How to Straighten Air Conditioner Fins

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Updated February 11, 2023

Many consumers put a lot of work into finding the best air conditioner for their living situation, only to have their compressor stall on them a couple of years later. One cause for this is that the fins become bent, often because of poor storage techniques.


  • Straightening coils require a specialized tool known as a fin comb.
  • Bent coils can cause an AC to be less effective and shorten the unit’s life span.
  • There are two types of fins: condenser fins, which are on the outside of the unit, and evaporator fins, which are inside the unit.

In this article, we’ll show you how to straighten air conditioner fins so you can keep your AC in good health and running for a long time. And for tips on how to properly stow your air conditioner, you can check out our resource that shows you how to store a window AC unit.

Other good maintenance ideas are learning how to unclog an air conditioner drain pipe, correctly sealing the gaps around a window A/C, and how to correctly turn off an air conditioner.

What is an Air Conditioner Fin?

Also known as compressor and evaporator fins, these grill-like aluminum strips are located on the back of your AC unit. They help the motor’s heat move away from the machine so that the inside doesn’t become overheated. Also, for more on regular maintenance for air conditioners, we have another article on how to test an air conditioner capacitor.

Insider Tip

Fin combs come in different sizes according to how many fins per inch the unit has.

Three Simple Steps for Straightening Your AC’s Fins

This form of air conditioner maintenance will work on both an indoor and outdoor unit and requires a specialty tool known as an AC fin comb. Once you have one, the process is super easy.

STEP 1 Power the AC Unit Down

  1. Unplug the unit from the electrical outlet.
  2. If your AC is a window unit, remove it from the window frame and place it on a sturdy table.

STEP 2 Use the Fin Comb to Straighten Crooked Condenser Fins

  1. Line up the fin comb at the top of the fins.
  2. After matching the teeth of the comb with the damaged condenser fins, lightly drag it in the same direction that the fins run.
  3. Continue to comb the aluminum fins until they are all straightened.

STEP 3 Use the Fin Comb to Straighten Crooked Evaporator Fins

  1. Unscrew the screws that secure the access panel, then remove it.
  2. Locate the evaporator coils inside the machine and repeat the same motion as you used on the AC condenser fins.
  3. Once straightened, screw the access panel back onto the AC unit.


Leaving your AC unit sitting unused for prolonged periods can weaken the AC unit’s cooling capacity and can even lead to major damages down the line.


Why are bent fins a problem?

Fins allow the unit to circulate air. If the fins are bent, it cuts off airflow, reducing the cooling effect and putting the unit’s components at a greater risk of being damaged.

How do you choose the right fin comb?

Fin combs are sized by fins per inch. You can determine the size you need by getting a tape measure and counting how many fins per inch there are on your AC unit.

When should you replace your fin comb?

Replace your comb when the ends lose their pointiness. Also, if you purchase a new system with a different number of fins per inch, you’ll need a new comb.

STAT: If, for some reason, you can’t measure your AC’s fins per inch, the average number on an AC unit is 10-12 FPI. (source)

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