Why Is My Car AC Blowing Hot Air?

Diagnosing the symptoms of blowing warm air in your car

The lack of refrigerant is the major reason why your car AC could be blowing hot air. Other reasons could be a faulty compressor and/or condenser.

Sometimes, it’s the cooling fans that are broken. However, this could also be a result of a problem with your car’s electrical system.

How Does A Car AC System Work?

There’s got to be a right way for things to work, for there to be a wrong way. A car AC is meant to regulate the car temperature in your car, keep it cool.

Before we try to dissect the reasons why your AC is acting the wrong way, let us first understand how a car air conditioning system work.

A cycle that ends with cold air being blown at you starts with the conversion of a gaseous refrigerant to liquid and back to gas moved into the evaporator.

At this point, air from outside is blown over it, which is then sent to the cabin after it has been cooled.

In this article, we will take a look at the 5 component parts of an air conditioning system that makes this possible.

1. Compressor

It’s important to know that Refrigerant-2 (R-2) is the accepted refrigerant for air conditioners today, replacing Freon, which was discovered to have adverse effects on the ozone.

The refrigerant comes in low pressure and low-temperature gaseous state. The job of the condenser is to ‘compress the refrigerant to an opposite high pressure and high-temperature gas.

2. Condenser

Following the cue of the compressor, the condenser basically takes the heat out of the refrigerant, preserving the high pressure while lowering the temperature and converting it to liquid.

This is done in a process similar to that of a radiator, and with the help of a pair of cooling fans found over the condenser.

3. Reciever Or Dryer

This looks somewhat like a cylinder. It contains desiccants, which is a substance that absorbs moisture.

The job of the dryer is to filter the now liquid refrigerant through these desiccants, to remove any traces of moisture from it.

The purpose of this is to prevent the refrigerant from freezing. Frozen refrigerant can cause all manner of problems in the air conditioning system.

4. Expansion Valve

This controls the amount of coolant that passes through the AC system, thus the ‘valve’ in the name. The ‘expansion’ in the name denotes that an expansion takes place in this component.

This expansion reduces both the pressure and heat of the refrigerant, reverting it to a gaseous state except now with low temperature and low pressure.

Some system has an orifice tube in place of an expansion valve and an accumulator instead of a dryer. Both alternatives have similar modes of operation with the same results.

5. Evaporator

This is the final component of the air conditioning system, and where the last phase of the cycle occurs.

This phase involves the passing through of the refrigerant through the lines found in the evaporator.

The heat is absorbed and released outside, leaving the refrigerant at about 32 degrees of temperature.

The fan then blows over the evaporator, delivering the cold air into your car, through the cabin.

The process begins all over again with the refrigerant making its way back to the compressor in gaseous low pressure and low-temperature state.

5 Reasons Why Your Car AC Is Blowing Hot Air

  1. Leaking refrigerant
  2. A faulty condenser
  3. Electrical malfunctions
  4. Faulty/broken cooling fans
  5. A faulty compressor

These are the primary reasons why your car feels like a sauna rather than a winter day.

1. Leaking Refrigerant

This should be one of the first things to suspect or check when your car AC begins to blow hot air.

Although it may be difficult to spot exactly where a leak might be coming from, given the gaseous state of refrigerants, but it is possible.

If you observe oily substance around hose connections, there is a chance a look could be coming from there.

2. A Faulty Condenser

Car condensers are usually found in the front of a car. There is a possibility of debris getting trapped and blocking the condenser.

This prevents the condenser from doing its work of cooling the refrigerant. This in turn makes your refrigerant overheated, and thus deliver hot air to the car chamber.

3. A Faulty Compressor

The compressor is what begins the cycle which produces and circulates cold air. A good compressor gone bad is often a result of not using it for long periods.

So, even on weathers when you may not require the AC, run it for at least 15 minutes, just to make sure the compressor has some time to work.

4. Electrical Malfunctions

The air conditioning system of your car requires electricity to function. And electrical problems are not news for cars.

A frayed wire will result in your AC system getting inadequate or no electricity at all. No electricity equals hot air.

5. Broken Cooling Fans

The cooling of refrigerants in the condenser is also thanks to the pair of fans that blow over them.

If this phase in the cooling cycle is affected by perhaps a broken fan blade, then the air in your car will be anything but cold. Warm at the very least.

What To Do

Now that you’ve identified a problem, what do you do? The best line of action is to take your car to a doctor. A car doctor.

The automotive technician will add a leak tracer dye to the air conditioning system to identify where the leak is coming from using a black light.

This is an easy way to find out if the problem is a result of a refrigerant leak.

But if the problem comes from other parts, the mechanic should have them looked at and offer his advice on whether a repair or a replacement would be a preferred course of action.

Lifespan Of AC System Components

It’s important to know how long the parts of your car are supposed to last.

Especially the components of your air conditioning system. This will help you guess what may or may not be the cause of your AC blowing hot air.

Your condenser and compressor are expected to last for 8 to 10 years on average before they should be repaired or replaced.

It’s a good idea to have your air conditioning system checked when you take your car for general maintenance.

This will cost you just about $100 or less, which is more than what you will pay in the case of damage. Bringing us to our next point.

How Much Does It Cost To Fix Your AC?

You can’t have your mouth agape at discovering what it might cost you to have your air conditioning system repaired in the event of a problem like when it blows hot air.

So I will save you that embarrassment. The cost will vary from one component that is damaged in the AC system and the degree of the damage.

A simple recharge of your AC system will cost as low as $100 – $140. Replacing or repairing of hose would cost approximately $500.

For minor compressor repairs, you should be looking at $170 – $730. If the damage is major, then the cost will step up to cost ranging from $4000.

Prevention, they say is better than cure. Apparently, less expensive too.

Is It Worth It?

This is quite a subjective question. If you have a fairly new car and observe a problem in your AC system, then Yes! you can definitely get your AC fixed and be guaranteed your money’s worth.

The opposite might be the case for an older car.

The problem with older cars is that it’s not just that it has one problem after another, but the fixing of one problem might just lead to another problem.

So, you could fix the AC today, and tomorrow it’s the steering. In that case, I say, let it be.

Can I Fix It Myself?

Between having to endure the heat coming from your AC and the possible cost of repair, there might be the temptation to try to fix the AC by yourself.

Well, that shouldn’t be a problem if you have some knowledge or experience with automobile repairs. But it might be counterproductive if you just want to wing it.

The AC system of a car is rather complicated. It would not just take a professional to fix it, but an experienced professional to put things in place and get things working again as they should be.

So, if you decide your AC is worth saving, you will need to suck it and hire a professional. Or eventually you risk paying an extra cost for undoing your failed attempt before doing it right.

In case, you want to know how to fix your AC that blows hot air, then I highly recommend you to watch this YouTube:

Conclusion

It can be very uncomfortable, maybe even downright unbearable to drive a car with hot air blowing in your face.

Especially when the weather is at extremely hot temperatures. Calm yourself down, literally, count the cost and get your AC fixed. It’s the only way to drive.

Written by Yusuke Kohara

Hi there! My name is Yusuke. I write about automotive topics for Car Proper. I love cars and have a passion for writing helpful articles on tools, car accessories, and how-to to help my readers solve their problems. In my spare time, I'm either working out, reading the book, or spending time with my family. I also work for a digital consulting agency.

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