Here's Why Your Car's AC Isn't Blowing Cold
Your car's air conditioner makes all the difference on a hot summer day. So, if you have cranked up your car's AC dial to the highest number, and it's not blowing cool air like it's supposed to, that could be both annoying and alarming. In some cases, you can hear the fans whirring, but nothing. In other cases, both the fan and air conditioner don't seem to be working right. Well, there are a bunch of reasons why this could be happening.
You might be thinking your vehicle just needs some refrigerant. But sometimes, that's not the fix your vehicle needs. Your car's air conditioning system comprises multiple intricate parts that come together to produce the cool air that circulates and brings you some comfort. If one component isn't working properly, say there's a leak, a broken belt, or a bad condenser, the AC might struggle to work as it should. Now, let's get into all the details of those parts and what may be wrong.
How your car's AC works
Your car's air-conditioning system consists of five main parts: the compressor, the condenser, the accumulator (or receiver-drier), the expansion valve (or orifice tube), and the evaporator. It works in a loop, starting with a fluid called the refrigerant, which you might know as AC gas. The refrigerant, which is just gas at this stage, gets squeezed by the compressor (a pump driven by your car's engine through a belt).
This squeezing action heats up the refrigerant and pressurizes it. After leaving the compressor, the hot, pressurized gas moves to the condenser, which is at the front of your car, near the radiator. As the car moves, air flows over the condenser's coils, cooling the refrigerant down. This process turns the refrigerant from a hot gas into a cooler liquid.
Before the refrigerant can continue, it passes through a filter called the accumulator (or receiver-drier in some systems). This part removes any moisture or dirt from the refrigerant. Removing moisture is important because water in the system could freeze and block the flow or cause damage.
Now, as a liquid but still under high pressure, the refrigerant arrives at the expansion valve (or orifice tube). This part controls how much refrigerant gets into the evaporator. It drops the pressure of the refrigerant, causing it to cool down further and turn back into a gas.
Finally, the evaporator gets to work. Located inside the car's dashboard, it extracts heat from the air inside the vehicle, cooling it. Then, a fan blows this cooled air back into the car.
When any of these components has a problem
When any part of the AC system is not functioning correctly, you might not be able to enjoy the circulation of cool air in your car. If the compressor isn't working properly, perhaps due to a broken drive belt, or general wear and tear, the refrigerant won't get pressurized correctly.
The condenser cools the hot, pressurized refrigerant and converts it back into a liquid. If it's blocked by debris, damaged, or the airflow is obstructed, it can't properly dissipate heat, and the system can't cool the refrigerant, which means the air blown into your car won't be cool.
If the accumulator malfunctions, moisture and dirt can gather in the system. This component cleans and dries the refrigerant. Moisture, in particular, is problematic because it can freeze, causing blockages that prevent the smooth flow of the refrigerant, or it can react with the refrigerant to form corrosive acids that damage the system.
If the expansion valve, which regulates the amount of refrigerant flowing into the evaporator, gets stuck, it's another problem. If it's stuck open, too much refrigerant flows into the evaporator, and doesn't get cold enough. If it's stuck closed, not enough refrigerant passes through, and the evaporator can't absorb enough heat from the air.
The evaporator removes heat from the car. If it's frozen over, which can happen if there's too much moisture in the system, air can't flow through it properly. If it's dirty or damaged, that's another factor that affects its ability to extract heat.
Last but not least, if you're low on refrigerant, which you might know as AC gas, perhaps because of a leak, it'll be difficult to get the system to cool your car.
What to do to get your car's AC to cool again
Now that you understand all the parts that make up your car's air-conditioning system, we hope you realize how each component if disturbed, can cause your car to not cool. Not understanding this can cause you to make maintenance mistakes that just generally make your car less reliable.
If the refrigerant is low, first, you have to ensure there are no cracks or leaks in the hose containing the refrigerant. Simply adding more refrigerant won't fix the underlying problem. You might need a professional mechanic for this because finding leaks can be tricky.
Sometimes, all it takes is to fix a crack, repair a fuse, or clean out a clogged condenser to get your air-conditioning system pumping cool air across your car vents. However, diagnosing the problem isn't always so straightforward.
The AC system works closely with your engine, and while there are engine maintenance tasks you can handle by yourself, having a professional mechanic diagnose the AC system is always a good idea. They have the tools and expertise to quickly identify problems and repair or replace what needs what correctly.
You might be able to save money by replacing your car's air filter. For general maintenance, according to Consumer Reports, it's not such a bad idea to open the windows for a few seconds while driving and waiting for the AC to cool. Because of the way your car's AC system is designed, it actually works faster when the engine is running.