Imagine driving peacefully on a bright sunny morning, listening to your favorite music, and enjoying the scenery around you.
Now, imagine that your car’s air conditioning system suddenly stops blowing cold air. How would you feel?
Absolutely desperate, of course! Any problem in your car that has to do with air conditioning can be very distressing, especially if you live in a hot country. Let’s take a quick look at the possible reasons for this malfunction.
9 Causes of Car AC Not Blowing Cold Air
The most common reason why your AC is not blowing cold air is due to an empty AC system, which is caused by a leak. It can also be caused by a faulty AC pressure switch, a bad compressor, or a damaged AC condenser. In more rare cases, it can also be an issue with your heat controller.
The main issues that occur with the car’s air conditioning system are due to poor maintenance. Here is a more detailed list of the most common causes of a car AC not blowing cold air.
1. Empty AC System
Your AC system is filled with an ac refrigerant, making sure the whole system is working correctly. This refrigerant system is under high pressure, and it can reach 15 bars when the car is running.
For the AC system to work properly, it needs this pressure and a specific amount of refrigerant.
If you leak in the AC system, the pressure will get lower and lower, until it finally stops working at all.
The AC system also leaks very slowly through hoses and other places. This is an extremely slow process, though, and you can expect to refill it every 6-7 years.
If you haven’t refilled it in 6-7 years, it is definitely time for a refill. If you filled it more recently than that, it is time to check it for leaks.
Only let a certified workshop with the proper equipment do work to your AC system. The AC system should always be checked for leaks before a refill.
RELATED: Does AC Leak Sealer Work?
2. Faulty AC Pressure Switch
There are two AC pressure switches in your car that monitor the high-pressure side and the low-pressure side of the air condition system for safety reasons.
If the pressure gets too high, it will stop the AC compressor from cooling the system anymore. This is a safety mechanism. The same is true if the pressure gets too low.
If the AC pressure switch is faulty, it can give the AC compressor faulty signals to stop – even if it shouldn’t – and this will cause your AC system not to function at all.
3. Faulty AC Compressor Clutch
Some car compressors use a clutch inside the air compressor. The serpentine belt powers the air compressor pulley, and when you activate the AC, the clutch connects the air compressor to the pulley. This makes the AC compressor to spin and power the AC system.
If this clutch is too worn, it may cause the AC compressor not to start at all. You can replace this clutch in many AC compressors, or even remove shims for the clutch for it to work a little bit more.
Most newer cars have a variable AC compressor, though, and in this case, no AC compressor clutch can fail.
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4. Faulty AC Compressor
The AC compressor clutch isn’t the only thing that can be damaged. The compressor itself can also fail if you are unlucky. The AC compressor pumps refrigerant around in the AC system for it to cool properly. Occasionally, the pump fails and stops pumping at all, and this will cause your AC system to blow hot air.
If the AC compressor fails, you often have to flush the whole AC system afterward, because there might be metal pieces everywhere.
5. Damaged AC Condenser
The condenser is installed in the front of the car, and it transfers heat away from the evaporator inside the car. The AC condenser is often installed in front of the radiator, and this means it sits in a very exposed position. Stones and other pieces of detritus can damage it when your car is traveling at high speeds.
This often causes the AC condenser to start leaking refrigerant. You will usually need to replace the AC condenser at least once every 10 years.
6. Damaged Condenser Fan
The condenser needs wind passing through it to remove the heat properly. As you might imagine, wind won’t pass through naturally if your car is moving at a low speed. For this, your car needs a fan so that air is pushed through even when your car is moving slowly.
If this fan fails, there might be a problem with the AC system at lower speeds. If you notice that your AC is working at higher speeds, but not at lower ones, there could definitely be a problem with the condenser fan.
7. Clogged Cabin Filter
The cabin air filter is responsible for filtering the air that enters the vehicle’s air conditioning system. The filter catches all the dust and impurities that enter the passenger compartment and can, therefore, become clogged over time.
Also, a clogged cabin air filter leads to a deterioration in the air conditioning system’s cooling. It is recommended to check and clean the cabin air filter frequently. If you want to know more, you can read my article Why should I replace my Cabin Air filter.
If you feel that there is a meager amount of air blowing through the vents, it could absolutely be a clogged air filter.
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8. Faulty Blend Door Actuator
When you turn the heat controller on the AC control unit, there needs to be something that controls the heat inside the car. This part is called the blend door actuator, and it controls a flap that redirects hot or cold air inside of your car.
The setup can look a little bit different from car to car, but the main function is the same. If this actuator is faulty, your car might blow hot air out from the vents even if you need cold air.
9. Faulty Heat Controller / Air Condition Control Unit
The last cause on this list is a faulty heat controller. If this fails, it may send the wrong signal to the blend door actuator, and this may cause it to blow hot air instead of cold.
Most older cars have wires for this, but newer cars have an electronic signal between these, which can fail. The air conditioning control unit is often quite expensive. You should check the other possible causes on this list before deciding to replace it.
6 thoughts on "9 Reasons Why Your Car AC Is Not Blowing Cold Air"
KURT G HELM
It could be a faulty blend actuator. If this actuator is faulty, your car might blow hot air out from the vents even if you require cold air.
Magnus Sellén
That's true. Thanks for the input!
janet f winstead
yes I have a 98 jeep grand Cherokee I am having problem with my ac it work some butn itwill blow cold air when idleing and slowing down but when I speed upto drive at regular speed it does not cool what causes that
S. Lawrence
My air is cool when I first turn on, then gradually cools less and less ...My dealer tells me they have to drain the existing coolant to determine problem..I ask for just recharging and he says no..200 to drain and fill with dye to determine if leak..is this right
Hugo Joza
it sounds about right...do it
Lisa Wirth
We have a 2006 Corvette. The A/C is blowing hot. There is good air flow through the vents, but no cold air. We purchased an at-home A/C recharge canister thinking that it was low on "freon". Once it is connected, with the A/C on high and car doors open, when you push the trigger to recharge, the gauge immediately maxes out. The compressor appears to be turning, with no unusual noises. Any ideas?