Back in the day, a car’s AC system was viewed as a fancy addition. However, in the present time, having air conditioning in your car is seen as essential.

Can you imagine being gridlocked in freeway traffic in the midst of summer without AC? I didn’t think so. Therefore, when your AC starts playing up or stops working, it’s something you want to resolve as quickly as possible.

The problem lies in the fact that not a lot of us know how car AC works. I mean, we know it blows cold air. However, how does that process work? And what do we do when, God forbid, it stops blowing cold air?

That’s why we’ve put together this ultimate guide to your car’s AC system. In this guide, we’ll touch on how your car’s air condition works, what the different components that make your car’s air conditioning are, and address some of the issues that commonly arise with a car’s AC.

How does car AC work?

First off, we’re going to take a look at how your car’s air conditioning system works. By this, we don’t mean pressing the on button, and cold or hot air blasts out. We’re going to break it down like Bill Nye The Science Guy. Don’t worry, this is easy to grasp.

An AC system cycles refrigerant by converting it from a gas into a liquid, and then back again. At the end of this cycle, it’s in a cold gaseous state inside the system’s evaporator. At this point, outside air blows over and cools, and is sent out to you and your passengers.

All in all, your auto’s ventilation system has 3 primary functions:

  1. Increase the internal temperature in your vehicle (a must in winter)
  2. Cooldown the car interior during the hot summer months
  3. Defrost your windshield

An AC system - sometimes referred to as a climate control system - is located in the hood of your car.

So far so good. However, what parts make all this happen?

What are the different car air conditioning system components?

Now you know how car AC works, it’s time to look at the different parts that form the system and make the above process possible.

1. Compressor

A compressor drives your whole AC system. It runs off a pulley attached via a belt to the crankshaft of your engine. This powers between 5 to 10 pistons (depending on your car model).

Low pressure and low-temperature gas is sucked in, and is then compressed into high pressure and high-temperature gas. The AC compressor receives power from the crankshaft, which is controlled by the compressor clutch. This gas is then sent to the next component of the car AC system - the condenser.

2. Condenser

The condenser sits right in front of your radiator. Its primary job is to cool down the aforementioned high pressure, high-temperature gas and turn it into liquid.

When the AC system’s refrigerant reaches the condenser, it cools and liquifies. This process produces a large amount of heat, which is removed by the air flowing outside the condenser.

3. Reciever/Dryer

Once the refrigerant is turned into liquid, it’s sent to the receiver-dryer. The filters in the receiver-dryer remove harmful debris that could damage the AC system, such as dirt, dust, and metal, while the desiccants remove any moisture.

Moisture that is leaked into the refrigerant could be dangerous for all of these components. Therefore, the receiver dryer’s job is to remove it all from the refrigerant.

4. Expansion Valve

The receiver-dryer sends pressurized refrigerant to the expansion valve. This part allows the refrigerant to expand by removing all of its pressure.

And, after the refrigerant expands, it drips into the evaporator.

5. Evaporator

The evaporator sits inside your car’s air cabin filter. When it receives low-pressure gas and cold refrigerant, it removes heat from inside the cabin, Then, the blower fan circulates cold air by pushing it through the evaporator

After that, the whole process repeats
If you’re more of a visual learner, here’s a handy visual aid from Quora on how car ac systems work:

Common car air conditioning issues

Here at FixMyCar, our mobile mechanics have noticed several recurring issues or questions from customers around their car’s air conditioning systems.

Here are a few of the common issues and questions that have been asked and, hopefully, the answers you’re looking for.

Why does my car AC smell like vinegar?

Bit of a weird one, right? However, if you’ve ever been in the position where your car has started to smell like a salad, you’ll be nodding your head at this one.

Before we answer this, we advise you to double-check if the smell is coming from your air conditioner. To do this, drive around without operating the AC. If there’s no smell, you’ve got a stinky air con.

There are a few different reasons why your AC might smell like vinegar:

  • Mold buildup - Air conditioners give off a large amount of condensation, which can turn to mold and mildew if it doesn’t completely dry.
  • Decaying natural material - If you have leaves or other kinds of natural materials lurking in your AC and its vents, it can eventually ferment, turn to alcohol, and cause a right stink.
  • Ozone emission - Your electric air conditioner motor could be emitting ozone, which is known to have a sour smell - especially when mixed with one of the above.
  • Old air conditioner filter - You may just need to switch this up for a new one.

If you’re noticing a sour or vinegar-like smell coming from your car’s AC system, get in touch with a trusted mobile mechanic. They can identify the source of the stench and fix it from your own driveway.

Why is my car’s AC not blowing cold air?

There are several reasons why your car’s air conditioning system stops blowing cold air:

1. AC refrigerant needs a recharge - This is the most common cause of a vehicle’s air conditioner no longer blowing cold air. Thankfully, this is nothing to panic about. Recharging your AC refrigerant at home is pretty basic car maintenance. Or, of course, you get a quote from one of our mobile mechanics.

2. An AC system refrigerant leak - This can be challenging to detect as AC refrigerant - also known as Freon - instantly evaporates when it comes into contact with air. However, there are several scenarios in which a leak may have occurred, including an audible click when AC is turned off, AC cycles on and off constantly, and hissing sounds from AC (when the engine is off). AC refrigerant is a harmful and toxic chemical. Therefore, if you suspect a leak, get a professional in.

3. Fan motor has failed - This is a little easier to identify. It’s good to keep both of your front fan motors in proper working order so you can keep cool on the road.

4. Broken AC compressor - A damaging or failing compressor won’t be able to regulate refrigerant flow. This will cause the AC to not function properly and run hot.

How to tell if your car AC compressor has gone bad

Without a fully functioning AC compressor, your car’s air conditioner is about as useful as a chocolate teapot.

However, how can you tell when your compressor is going, or gone, bad? As mentioned, an AC system blowing hot air is a sign your compressor is on the wane. Another warning is strange noises.

If any of your car’s air conditioning system components break - including the compressor - you can expect to hear all kinds of noises. However, as mentioned, a hissing sound could also mean you’re low on refrigerant. Turn your AC off to see if the sound stops and then back on again to see if it resumes. If so, you’ve got an air conditioning problem.

Another sign of a nonfunctioning compressor is the clutch not moving. The compressor’s clutch allows the pulley to engage and disengage from the engine’s power. This means it’s only turning when it needs to be. However, the clutch can seize, which means the compressor is permanently activated. On top of this, the clutch can break. This stops the compressor from receiving engine power completely.

For this AC repair, another of the above, or one that’s not listed, stay cool and get one of our certified mobile mechanics to come to you.

Bottom line

We hope that you now have a firm understanding of your car’s AC system and all of its components.

As you can see, when it comes to identifying car air conditioning issues, it can be a little tricky to do without an untrained eye. If you’ve noticed a problem with your car’s AC system, it’s best to leave the repair to a professional.