How To Comb An AC Unit

Got bent fins on your AC? Aside from their unsightly appearance, bent fins contribute to stress on your AC system. This stress translates to inefficiency. To keep your air conditioner in good shape, we have prepared an easy-to-follow guide on how to straighten those fins out.

You can comb an AC unit by following these easy steps:

  1. Examine the damage.
  2. Measure fins per inch (FPI) of your condenser/evaporator.
  3. Purchase a fin tool with the correct head (matches the number of fins per inch).
  4. Turn off the AC.
  5. Remove any covering to expose the condenser and evaporator fins.
  6. Use the tool to comb along the direction of the fins.

Now you could very well use the services of AC maintenance professionals, but that will cost a fortune compared to doing it yourself. If you plan to go the DIY route, then read on to learn the various things you should consider to avoid mishaps and ensure a top-notch job.

Bent and dirty air conditioning coil fins, How To Comb An AC Unit

Straightening AC Fins Out

Follow this guide to comb your AC unit:

1. Examine the damage—the issue with crooked fins

Most residential air conditioners are made up of similar parts, including the evaporator and condenser.

Evaporators are responsible for absorbing heat from your home, while condensers eject the gathered heat outdoors.

Both are coils (typically made of copper) with "fins" attached. The fins maximize surface area to increase heat transfer via the air passing through.

If these fins get bent, damaged, or blocked, the lower surface area results in less heat transfer and air restriction.

Your AC will work more than it usually would, putting continuous stress on its numerous components while consuming more energy and leading to higher utility costs.

The good news is that even when the fins get deformed, you can straighten them out. You can use an inexpensive implement called the fin tool. More on that shortly.

2. Measure Fins per inch

FPI, or fins per inch, is the number of fins you'd find in an inch. It's vital to determine the FPI of your evaporator or condenser to find the right tool for the job.

3. Purchase a fin tool 

Also called a fin comb, this tool looks just like (well, you guessed it) a comb. It comes in various shapes and sizes, with some types prioritizing ergonomics and comfort of use. Some are compact enough to fit in a pocket.

Regardless of appearance, look for a fin comb that matches your evaporator’s or condenser’s FPI.

Check out this Malco fin straightening tool on Amazon.

4. Turn off AC

Safety first! To avoid electrocution, turn off the power supply to the parts you’ll be working on. You can even shut off the entire system by unplugging it or shutting off the circuit breaker.

However, if you think doing so will convert your home into an oven, then you should  plan to do this process during cooler weather.

Don't worry, though, as the process won't take long. It isn't tedious enough to take much time out of your day, but if you're afraid it will (perhaps you have several air conditioners that need fixing), you can stop at this point and call a professional.

This will be a perfect opportunity to do overall AC maintenance.

5. Remove covering to expose the fins

Aside from turning off your AC, prepare the work area by removing any obstructions.

Air conditioning unit mounted on metal brackets outside a small building

If your air conditioner is the split-type sort with the condenser outside, remove any fences you may have placed to protect the unit from pets. Unscrew and remove any covering that it came with to expose the fins.

You most likely won't have to tinker with the evaporator, because it rarely receives stress enough to dent the fins. The condenser, on the other hand, is constantly exposed to falling tree limbs, canines, felines, snow, hail, and extreme outdoor weather, so it's more important to check the condenser.

For some through-the-wall air conditioners, you likely won't have to unscrew anything. Just remove the filter by sliding it out; you'll find the evaporator fins underneath.

However, if you want to reach the condenser on these types, you'll have to remove the unit from the wall or go outside, because you'll find it on the back.

6. Use the combing tool

The fin tool has "teeth" that fit into the crevices between each fin in your evaporator or condenser. While the teeth themselves aren't sharp, the fins sometimes are. Safety tip: Wear soft gloves with a firm grip to avoid direct physical contact with the fins.

Our goal is to move from this:

Bent and dirty air conditioning coil fins

To this:

New air conditioning coil replacement

Use the tool to comb in a parallel direction, mostly up and down, as shown in the video below. Go back and forth until you find that the kinks are straightened.

It'll be hard to make them look brand new, but you’ll see the difference. There should be visible space between the fins.

To find out, you can run a flashlight from behind to see if the light passes through. Just a bit of light passing through is a sign that you did a good job.

With the fins exposed, this is also a prime opportunity to clean them. Run the comb through the entire evaporator or condenser, even the sections without any visible kinks.

Doing so will remove any debris that might have been stuck there for months or even years, in some cases. As with straightening the bent fins, clearing the fins of obstruction will achieve the same result: a more efficient machine in the long run.

How do you clean AC condenser fins?

As suggested earlier, fixing bent fins presents you with an opportunity to clean them. The tools you can use include:


With the fins exposed, the first thing to do is clean them with a vacuum cleaner. Vacuum in an up-and-down motion to avoid squishing fins sidewards should you accidentally touch them.

Cleaning air conditioning filter using a small vacuum

Fin brush

Although the fin tool that you use can also remove debris, there's another handy implement better suited for this task.

The fin brush, which resembles the palm-sized paintbrush typically used to paint walls, comes with softer bristles that you can regularly use on those delicate fins for the sole intent of cleaning them.

The bristles are flexible enough to avoid denting the fins while sporting enough grit to remove built-up dust, dirt, and any airflow obstruction.

Coil cleaners

Hardware stores often carry products labeled as AC coil cleaners. You can use these to spray on the coils and fins, leave them for five minutes or so, then gently use a garden hose to rinse if needed.

Avoid spraying other parts of your AC (e.g. motor fan), as this could damage them. If you're unsure of how to use these products, you can refer to the AC manual first or hire a professional to do the cleaning job—along with overall maintenance.

Why do AC fins get bent?

The reason why AC fins easily bend is due to the material typically used—thin strips of aluminum. They are inexpensive and heat-conductive but can easily deform when any of the following occurs:

When hosing them in your backyard

Aside from keeping the internal workings dry, take caution in using too much water pressure. That's one of the most common causes of bent fins. 

Physical damage

You can prevent physical damage to your outdoor unit by putting it in a cage or laying a fence around it. The most common culprits for physical injury to your condenser can be avoided by taking this step.

Encasing your outdoor unit can help prevent exposure to the elements. Just make sure that you don't cover it completely. This could block the airflow and encourage moisture buildup.

Can you replace the AC fins?

While a fin comb can straighten bent fins, it can’t remedy corroded or missing ones. If this is the case, professionals can replace the entire condenser fin assembly for you. It’s best to call before summer arrives as they’ll be busy by then. 

In Closing

Bent and dirty air conditioning coil fins

While it may be difficult to diagnose or repair a broken AC yourself, fixing the fins is an easy way to contribute significant savings in utility bills. We hope we have helped you with our detailed discussion on the steps to properly comb your AC unit.

Before you go, check out these other posts:

Should AC Be Serviced Every Year?

How Often To Change AC Filter In A Home With Pets

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