Kia Optima AC Blows Warm At Idle? Know The Common Reasons Why

Do you encounter a problem with a Kia Optima AC blows warm at idle? 

When the weather is humid and hot, this is the last thing you would like to be going through. After all, it does not make the drive any fun at all. 

You may be counting on cooler air once you get into your vehicle after being out in the sun. However, when the air that comes out is warm while on idle, this may be a concern with your car AC unit. There are also quite a few reasons why this may happen, which is why it is important to know the causes to figure out the best way to go about the fixes.

Keep reading to understand the ways on how you can get this problem resolved.

kia optima ac blows warm at idle

Kia Optima AC Blows Warm At Idle

First, let us take a look at how your car AC operates to understand the potential reasons why your Kia Optima AC blows warm air at idle. 

Your car’s AC needs a refrigerant to work. There are also some components in it such as the condenser, orifice tube, accumulator, compressor, and evaporator. Your compressor also compresses your refrigerant and it turns into liquid. Once it has compressed the gas, this gas heats up and creates a high pressure that then forces your refrigerant to enter the system to your condenser.

Now, the condenser has a coil section, in which cool air passes over. Hence, this transfers heat from your compressed gas into the air. 

As for the refrigerant, it enters the dryer to eliminate contaminants. After purifying, this compressed refrigerant enters the expansion valve and pressure is stripped off from it. Once it has traveled the evaporator, this makes the refrigerant clean, cold and dry.

To make sure that there is cold air blowing out of the AC unit, air must be sent through your newly cold refrigerant found in your compressor tank. This should cool down and be released through your blowers.

To create the gusts of cold air blowing out of your car’s AC, air is sent through this newly cold refrigerant in the compressor tank to cool down and then blown out through the blowers.

Why Your Car AC Blows Warm Air At Idle

There are a few reasons why you may be having warm air blows by your car AC when idle. Here they are:

1. Condenser fan issues

Your cooling fan found in your condenser is the most common culprit when you notice warm air coming out of your AC when on idle. This means that there is damage to the condenser fan, or it is not running at its optimal performance. Moreover, it may not be capable of cooling down heat from the refrigerant through your condenser.

When your vehicle is running at a high speed, there is no need for the condenser to use the fan to cool your refrigerant since there is ample air passing through this component. However, when you are on idle, your fan is what makes the refrigerant cold.

This is why it is important to inspect your fan’s connections. See if these are starting to get loose, or perhaps the fan is no longer sitting properly in the right slot. There may also be some damages to the fan that prevents it from performing as it should.

2. Low refrigerant level

Next up, you need to keep in mind that your refrigerant gets used up whenever you run the AC. So, once the level has gone down, and it is no longer adequate, this causes some problems with the AC unit. This is why there is no longer any cold air coming out when you are on idle.

Your compressor pumps the refrigerant more efficiently when you run at a higher speed. However, there is a struggle when you have the vehicle sitting idle. This is why you will have to refill your refrigerant either by doing it yourself or by taking it to a mechanic. 

You may also want to observe for a low refrigerant issue if there is no sound of your clutch engagement whenever you turn the AC on. Your compressor makes it possible for the pressurizing of the freon by your compressor. This also reads the freon levels. So, if activation does not happen, there may be insufficient freon.

It is also possible for a leak in your condenser, which brings the refrigerant level down. The seals of your condenser, as well as the tubes, are subject to wear and tear over time. Thus, these can break or crack, which makes a leak possible. 

When simply making an ocular inspection of a leak, you may not notice it right away. But you can have a mechanic check it or you can use a trace dye to detect any leaks in your condenser. You can also try adding more refrigerant to bring it to the right level then turn your AC on. Then, if you have seen some bubbles come out after spraying soapy water to your suspected leak areas, then there is the answer. 

Aside from leaks, clogs may also form when debris or foreign objects get lodged into the condenser. These obstruct your fins, which prevents the AC from blowing cool air when idle.

Over time, your condensers may accumulate some clogs, which is why you should do your best to get this component cleaned and maintained.

And lastly, you may have an overheated engine. So, if you have a very high engine temperature, this also minimizes the air temperature coming into your radiator and makes the air not cool at all.


There are many reasons why a Kia Optima AC blows warm air at idle. With all these things in mind, make sure to inspect potential causes of the problem and address it accordingly once you have identified the culprit.

Leave a Comment