Car AC smells bad when first turned on

Sometimes drivers will notice that soon after they turn on the air conditioning, a bad smell will be felt in the car. But why is this happening? We will find out in this article.

Car owners who often use a car AC have often come across the fact that a bad smell is felt as soon as the mechanism is turned on, more precisely, in the first minutes of its operation. The smell resembles more like a dead animal or a rotten fish that can be musty and harsh, or it can be pulled by moisture from stagnant water.

The bad thing is that most drivers often will ignore this smell by covering their nose or will open the windows or the door to get rid of the smell. If you have this problem is best to take care of it because this can lead to the failure of individual parts of the car AC system.

Why does the car ac smell bad?

Most often the causes of the bad smell from the AC system are moisture that forms on the air conditioning parts and also the presence of other rotten stuff. It is not difficult to find the exact location from where the unpleasant smell comes from. As practice shows, the place where moisture forms and other smelly stuff gathers, is the air conditioning evaporator.

car air onditioning Evaporato
AC evaporator

Because of temperature differences, on the AC evaporator, the ideal conditions are met for the moisture to form and debris to gather. In addition, odors can be caused by the technical device of the AC system itself, and not by improper use of the air conditioning.

When the AC is operating, the drawn air arrives in the evaporator where it is cooled and , logically, condensation forms on the its surface, which becomes the cause of all further problems.

When the drivers arrives at his destination and stops the car, already an amount of moisture forms on the evaporator. In addition, the dust and debris there will only accelerate the process. The condensation begins to warm up to the cabin’s temperature. These dozen of such changes will lead to that bad smell.

How to remove the bad smell from the car AC?

In car stores and on the market you should find a lot of products for cleaning the car air conditioning system. We will list below the most used.

Gas cleaning spray

A widely used method to clean the car AC is using a gas spray. To use the gas spray:

  • Start the car, turn on air recirculation in the cabin, remember, don’t take air from outside. 
  • Next, place the gas container so that it is in the flow of intake air and start to spray the agent.
  • After completing the process, do not turn off the air conditioner, close the doors, and leave the car like this for 10-15 minutes. 

This technique comes with advantages and disadvantages. The plus is that a minimum effort is required, and the con is that the cleaning may be minimal or nothing will change at all.

Use a special foam for cleaning

This is also another method for cleaning the car air conditioning system. It is better and more effective than the previous one. The recipient contains polyurethane foam and a hose that helps to spread the foam.

  • Before using it, it is best to start the engine and let it run until it reaches the optimum working temperature. After that, you should stop de car and remove the cabin filter.
  • After that, add the foam in the place of the cabin filter because in that place are the most car AC systems.
  • The foam will begin to expand on the air conditioning parts including the main source of the bad smell, the evaporator.
  • After about 20 minutes, the foam will begin to act against the debris and moisture that are present there. Let it act for another20-25 minutes.
  • When the cleaning procedure is done, turn the AC and let it work in different modes. This will help to dry out the remaining foam and removing the smell.
  • You should repeat the above steps after a while, even faster if the smell is still felt.
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Lysol Disinfectant Spray

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Nu-Calgon 4171-75 Evap Foam

How to flush an air conditioning evaporator?

On one hand, flushing the evaporator is considered the most reliable way to get rid of moisture and debris that causes the bad smell. On the other hand, this is the most difficult method and takes some time. You should note that the evaporator itself is one of the car’s AC parts which is charged with refrigerant (freon). 

Each car model has its own place for the evaporator, so there is no need to tell how to get there because this will depend on the car make and model. The best way is to go to an authorized workshop to carry out the maintenance there.

The evaporator should be cleaned thoroughly. You should also know that it is very difficult and almost impossible to remove all the dirt, mold, and bacteria from it, but also doing the cleaning in good conditions will surely be enough. After a while, the smell will appear again even with a thorough cleaning. During removal, you should be careful not to break the sealings.

How long does it take to clean the car air conditioning?

Removing and cleaning all the parts by hand is considered the most effective method for cleaning the common causes of AC bad smell. So, don’t expect to get it done in one hour. On average, it takes 2.-3 hours for the car air conditioning system to be cleaned.

How to maintain the car air conditioning?

We talked about how to get rid of the unpleasant smell in the AC system, but now it’s time to talk how to prevent or to delay as much as we can the AC bad smell. 

First of all, pay close attention to the cabin filter, change it as often as you can. Cabin filters are not expensive, but by buying a cheap filter, you will speed up the process of mold formation, so you should buy a cabin filter with carbon, which is a better alternative

Secondly, dry the air conditioning evaporator until stay parked longer, overnight in a garage, or in a parking lot. It is recommended to calculate the time the AC is turned off to the moment the engine is turned off. You should stop the engine at least after 3-5 minutesafter turning off the air conditioning, preferably 10-15 minutes

To do this, turn off the AC, but leave the fan working, due to the airflow, the evaporator will dry out. Thus, the accumulation of moisture and dirt will take place in a very long time.

The appearance of an unpleasant odor is the first sign that it is time to look at the cabin filter and secondly to clean the evaporator. Therefore, you should start doing maintenance as soon as possible.

How to remove bad odor from ca AC video

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