Car AC Smells Bad When First Turned ON: 3 Causes & Fixing

Car AC Smells Bad

You are in the fresh mode, started the car, and wanted to go on a picnic, As You turned ON the AC your mode suddenly changed. You realized that your AC blows an unpleasant odor. Your mood changes, and shuts OFF the car AC. Apart from this, the car’s bad AC smell is also unhealthy for breathing and creates lung diseases, It should be addressed.

According to the research, extensive use of air-conditioners (ACs) indoors as well as while traveling in cars has increased the risk of atopic sensitization and it may alter lung function.

In this powerful guide, you are going to learn the three wild causes behind why the car AC smells bad when first turned on and how to fix it.

Related Post: 11 Painful Reasons Why Your AC Blows Warm Air

Car AC Smells Bad When First Turned ON

This page is divided into two parts, causes, and solutions. First, we will discuss the car AC’s bad odor causes, then their solutions.

3 Causes Of Bad AC Smell In Car

Here are the three causes of car air conditioner odor.

  1. Too Much Humidity
  2. Blocked Drain Pipe
  3. Dirty Cabin Air Filter

1. Too Much Humidity

Example of Mildew On A Loaf Of Bread
Example of Mildew On A Loaf Of Bread

Note that one of the most common reasons for a bad smell is an excessive amount of humidity in the cabin. Humidity enhances the growth of microbial such as bacteria, fungi, and other micro-organisms on the outside surface of the evaporator.

It is due to the high amount of humidity in the cabin forces to develop mold and mildew on the evaporator surface. This is the reason the car AC smells like vinegar or a musty or dirty sock type, which worsens the air quality and leads to many human lungs disease.

This is an Info
Whenever you turn OFF your AC, do not switch OFF the blower motor for at least 5 to 10 minutes to dry out the evaporator.

Related Post: How To Recharge Car Air Conditioner

2. Blocked Drain Pipe

Mold On Evaporator
Mold On Evaporator

In normal conditions, when the air passes across the evaporator, humidity in the air is condensed on the evaporator and seeps out via a drain pipe to the outside of the vehicle. If anything accumulates on the path of the drain pipe and gets blocked, the condensed water will accumulate in the evaporator case causing mold on the evaporator.

In short, the evaporator will sink in standing water and will lead to bacterial growth, which causes a bad AC smell. For your kind information, you can know the blocked condensate drain line when the water leaks inside the dashboard.

3. Dirty Cabin Air Filter

Dirty AC Air Filter

You might know that the cabin air filter filters the dust particles and pollens from the inside of the car. When the cabin air filter is clogged, it absorbs moisture, which is the breeding ground for microbial growth. So, when air passes through a moisturized air filter filled with bacteria, the car AC smells like a rotten egg.

Related Post: How Car Air Conditioner Works

How Do I Get Rid Of The Smell In My Air Conditioner

| 4 Easy Tips To Fix |

In this section, we are going to learn to fix the car AC’s bad smell due to mold formation. The car AC smells bad at first when turned ON, but after some time it goes away by itself. But, here is an interesting point, if the smell lingers after repeated usage then chances are mold has been created on the evaporator. So, here are four easy practical tips you can take to get rid of mold in-car air conditioners.

This is an Info
Starting the car AC after a long period, it smells bad for a while then goes away by itself. That is totally NORMAL.

Tip 1. Take Care Of Your First Line Of Defense

Cabin Air Filter is your first line of defense.

The first tip, you should take is for checking the dirty cabin air filter. The dirty cabin air filter smells like a rotten egg. Look for the dirty air filter and replace it with a new clean air filter. Take out the standing condensated water and make sure you have an open-drain pipeline.

Tip 2. Use Antiseptic To Kill The Microbial.

The second tip, you can use to remove the car AC’s bad smell is to use antiseptic. Spray with antiseptic into the exterior air-port (The base of the windshield outside near the hood, and is used to filter the air entering into the cabin).

Some people spray with an air freshener to fix the car AC odor. Honestly, that is not the solution. You have to completely eliminate the source of odor-causing microbe.

Related Post: Doing These Will Make Your Car AC Blow Twice As Cold

Tip 3. Make The Evaporator Coils Dirtless

The evaporator coil is subjected to dirt, which absorbs the condensated water. This condensated water is responsible for the unpleasant odor in your car AC. You can clean the evaporator coil by leaving the high-pressure water on the evaporator coil or with a foaming coil cleaning agent. This will remove the mold as a well bad smell.

Tip 4. Open The Blocked Drain Pipe Line

AC Drain Pipe
AC Drain Pipe

This is another tip to get rid of mold in-car air conditioners. An AC drain pipeline is fitted at the end of the evaporator assembly unit, which drips the condensated water out of the car.

A blocked drain pipeline will accumulate the condensated water at the base of the evaporator assembly unit, which leads to bacterial growth that causes a bad odor in the car.  Open the blocked drain pipeline, so that the condensed water can easily flow out of the car.

Frequently Asked Questions (FAQs)

Can I spray air freshener in my car vents?

The answer to this question depends on the type of air freshener you are using. The use of air fresheners is a personal preference. Some people prefer to use them in their car vents, while others do not. There is no right or wrong answer, it is simply a matter of preference.

However, there are some potential risks associated with spraying air fresheners into car vents. The main issue is that the air freshener chemicals can potentially build up on surfaces within the vent system and be released into the cabin of the car over time, which can be harmful to occupants. Additionally, spraying air fresheners into car vents can affect the operation of the ventilation system, potentially causing it to work less effectively.

Why does my car AC smell weird?

The foul smell emanating from your car’s air conditioner could be the result of various factors. One possibility is that the cooling coils are dirty and need to be cleaned. If the coils are not cleaned on a regular basis, they can become covered in mold and mildew, which will cause them to emit a musty smell. Another possibility is that the air filter is dirty and needs to be replaced.


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