How To Clean Car AC Evaporator Without Removing It

Josh Mitchell

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Josh Mitchell

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Holly Curell

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One of the keys to ice-cold air conditioning is a clean evaporator coil. Unfortunately, most car owners don’t realize that their evaporators can get dirty and require cleaning.

Luckily, cleaning an evaporator coil can be a good DIY project with some basic supplies, and removal isn’t required.

Key Takeaways

  • Dirty evaporator coil means that the AC will not be effective at cooling.
  • The hardest part about DIY cleaning the evaporator coil is reaching it. Once reached, you have to thoroughly clean with specialized cleaners. You must read the instructions of the cleaner thoroughly.
  • There are many tell-tale signs of a dirty evaporator coil including poor air flow, damaged cabin air filter, ratting sounds, bad odor, and AC lines freezing.  

What Does an AC Evaporator Do Exactly?

The evaporator coil is a primary part of every air conditioning system because it turns the warm liquid refrigerant from the condenser into gas.

The refrigerant gets cold during this process, which cools the air from the car’s vents.

After leaving the evaporator, the gaseous refrigerant returns to the compressor to repeat the cycle.

What Happens If It’s Dirty?

A little dirt on the coils isn't abnormal and won't cause major damage.

However, a clogged evaporator coil requires cleaning because the air conditioner will not cool efficiently if left unchecked.

How Often Should It Be Cleaned?

I rarely check the evaporator coil in my car because it is so hard to access. However, I would recommend checking the evaporator every year or two.

The evaporator should not get dirty enough to affect cooling capabilities as long as the cabin air filter is regularly replaced.

TL;DR: Clogged or bad evaporator coil can make your AC ineffective. This component should be inspected and cleaned every year or two.

Related Article: How to Flush a Car AC?


Cleaning the Car AC Evaporator Without Removing It (In 9 Easy Steps)

I would never remove the evaporator coil to clean it unless it was completely inaccessible and there are no other options.

The steps below keep the coil in place while ensuring a thorough cleaning.

Cleaning Car AC evaporator

1. Put On Your Protective Gear

It’s always important to wear proper protective gear when working on a vehicle.

Because cleaning the evaporator coil includes blowing dirt around and spraying cleaners, I always wear gloves and use eye protection.

Also, remember that the aluminum lines have pressurized refrigerant in them. Besides wearing protective equipment, be extremely careful when working around these lines.

TL;DR: Safety first; always wear protective gear. 

2. Find the Evaporator Coil

Now it’s time to locate the evaporator coil, which may be easier said than done. Buying a service manual is a good place to start.

Alternatively, many public libraries provide access to Chilton’s guides on their website.[1]

Likely, the most helpful option is a simple YouTube video tutorial.

There are walkthroughs for nearly every type of car, and a video makes it much easier to see and understand what is going on.

ACLAB note:

The most common location for the evaporator is underneath the dashboard and behind the glove box.

It is in a black plastic box containing the heater core, resistor block, and fan blower motor.

Older vehicles, particularly trucks, have their evaporator coil under the hood.

TL;DR: The hardest part about cleaning evaporator coil is first locating it. There are several tutorials available online for every car model. 

3. Access the Evaporator Coil

The hardest part of cleaning the evaporator coil is getting to it.

This is where a tutorial, guide, or YouTube video really comes in handy.

Every car is a little different, so finding the exact removal procedure is vital.

However, the process typically involves removing the glove box, then using a small socket to remove all of the screws in the plastic housing.[2]

I like to use an impact driver or a cordless ratchet to speed the process up and reach those tight spaces.

With all the screws out, the bottom part of the casing should drop down. However, there may be a couple of bolts going through the firewall.

TL;DR: The hardest part about cleaning evaporator coil is first locating it. There are several tutorials available online for every car model. 

4. Inspect for Dirt

After removing the AC casing, I take a quick look at the evaporator coil, the heater core, the resistor block, and the blower motor to ensure there is no loose debris.

Since accessing the evaporator coil is so time-consuming, inspecting and cleaning these critical components is worth a few extra minutes.

The most important thing to do is to ensure nothing large is in the air conditioner housing.

This includes leaves, acorns, or other items that could clog up the blower motor.

Not only will these cause damage, but they are also a sign that the air filter is likely damaged.

I will clean the coils once I’ve removed any loose particles I can with my hands.

TL;DR: Remove the larger and loose debris before applying the cleaner.

5. Apply The Cleaner

After removing any junk in the air conditioner assembly, it is time to clean the evaporator coil.

This can get messy, so putting some plastic on the car’s floor is a good idea.

Next, I get out my coil cleaner and apply it to the evaporator coil. There are a few different kinds of coil cleaners.[3]

These include liquid cleaner in a spray bottle and a can of foaming coil cleaner in an aerosol can.

It is very important to follow the instructions found on the cleaner’s packaging. For instance, some need to sit longer than others.

ACLAB note:

Some cleaners are made specifically for the condenser coil, not the evaporator coil.

However, all cleaners must be sprayed onto the coils. I liberally spray the coils down and let them sit for a few minutes.

TL;DR: Apply the cleaners on to the evaporator coil. Make sure you have the right cleaner specifically designed for evaporator coil.

6. Brush the Evaporator Coil (Optional)

Next, I use a soft brush to carefully clean the evaporator coil. This step is optional but sometimes necessary if the evaporator coil is very dirty.

For instance, if the air filter rips and lets debris through.

My go-to cleaning tool is a soft brush with long bristles. It can be a little stiffer than a toothbrush, but too hard will bend the aluminum fins.

After spraying the cleaner, I let it sit for a few minutes to take effect, but I don’t let it dry.

To clean the evaporator coil, I brush it in the direction of the fins. If the fins go different ways, then I gently go over them with extreme caution.

If possible, I will try to brush both sides of the evaporator coil, but sometimes that isn't easy.

TL;DR: You may use a soft brush to reach the depths of evaporator coil for a thorough cleaning.

7. Rinse Off the Cleaner

Even though the evaporator coil is clean, the work isn’t over yet.

I always rinse the evaporator coil with water to get the cleaner out. I also like to rinse the heater core off if it looks dirty.

Depending on how much room there is to work with, I will often use a spray bottle with a narrow stream to flush the evaporator coil.

Ideally, I would use a larger stream, but catching the liquid in such a tight spot is difficult. A garden sprayer is a great option if there is enough space to work.

Placing a small plastic bin under the evaporator coil is a good idea to catch the dirty water coming out.

I don’t spend too much time flushing the evaporator coil, just enough to rinse the cleaner out.

TL;DR: Rinse the cleaner out with water. Beware of the spills.

8. Make Sure It is Dried

Once all of the cleaner is out and the evaporator looks good, the boring part starts. The evaporator coil needs to dry.

Unfortunately, there isn’t a fast way to get this part of the job done, and depending on the temperature outside, it can take a couple of hours.

I blow air through the evaporator coil to speed things up a little.

One way to do this is with a small blower, but canned air will also work. The goal is to blow out the bulk of the water rather than dry it completely.

After blowing out the evaporator coil, I will still let it sit out to air dry for a couple of hours before putting everything back together.

TL;DR: Wait until the evaporator coil has dried up. 

9. Reassemble the Air Conditioner

The final step is to put everything back together.

This part usually goes faster than expected, but it can still be a little tedious to make sure that nothing gets forgotten.

Since I don’t remove the evaporator coil to clean it, all I have to do is put it back in place.

I also check the heater core, blower motor, and resistor block are all in their proper location.

With everything in position, I put the plastic casing back together. A magnetized socket or screwdriver really comes in handy to put the screws back.

The final part to install should be the glove box, which will either snap in or bolt on.

ACLAB Tip:

However, before putting the glove box in, I replace the cabin air filter. Doing so ensures the evaporator coil stays clean going forward.

After everything is back together, I try out the air conditioner to check the airflow. The air should blow cold with a strong flow.

In addition to feeling the air, I also listen for any noises coming from the air conditioner assembly to make sure nothing is vibrating or rattling around inside.

TL;DR: Reassemble all the parts in the proper order.


Warning Signs That Your Car AC Evaporator Needs Cleaning

Because the evaporator coil doesn’t require cleaning very often, it’s important to be on the lookout for these signs that it’s time.

Warning signs
  • Poor airflow.
    The first sign that an evaporator coil needs cleaning is a lack of airflow and poor performance of your AC. When the coils get obstructed, less air can pass through the vents.
  • A torn air filter.
    A red flag that I use is a damaged cabin air filter. People often skip replacing this component, which can rip after many years of use. Once damaged, particles can pass through and get stuck in the evaporator coil.
  • Rattling sounds coming from the glove box.
    Junk rattling around is never good, and that is especially true with the air conditioner. The noise could be an acorn that made its way inside or a broken piece of plastic. Regardless, the AC assembly must be disassembled, and the evaporator coil should be cleaned.
  • Bad odor coming from the air vents.
    A stinky car is a real pain, and if the scent emanates from the passenger side near the glove box, something likely got in the AC system. In this situation, I would clean the plastic casing with bleach and then use the method above to clean the evaporator coil.
  • AC not cooling and lines freezing.
    An obstruction in the evaporator coil will limit airflow, causing the coil and lines to freeze. If the air conditioning lines under the hood have ice built up, the evaporator coil may be clogged.

TL;DR: From AC not cooling to rattling sounds and frozen AC lines, there are many tell-tale signs of a dirty AC evaporator coil.


FAQs

Can I Use Vinegar To Clean The Evaporator Coils?

I would not use vinegar; you should only use approved coil cleaners. Although vinegar is suitable for cleaning many things, it is acidic, which can corrode the aluminum coils.

If you try cleaning the coils with vinegar, dilute it in half and thoroughly rinse it off.

How Much Does It Cost To Replace An Evaporator In A Car?

The total cost greatly depends on the type of vehicle, the cost of the replacement part, and service rates in your area.

I’d expect to pay at least $1,000 for a replacement, which could go significantly higher. Contact a local service center for details and exact pricing.

How Long Does An Evaporator Coil Last?

Evaporator coils often last the life of a vehicle. In many cases, this is over 20 years, but they can also fail unexpectedly.

References: 

  1. https://haynes.com/en-us/chilton
  2. https://knowhow.napaonline.com/heater-core-replacement-a-beginners-guide/
  3. https://www.nucalgon.com/media/6560/20-s164_coilclean8pg.pdf
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Josh Mitchell

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Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

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