So, you jump into your car and it’s hot. You turn on the air conditioning to cool down, but within a few minutes the cool breeze turns warm again. You find yourself turning the AC off and on again to keep yourself comfortable while driving. If this sounds like a problem you’re having with your car’s air conditioning system, then this is the article for you.
With any luck, this guide will help you diagnose why your car AC keeps shutting off so that you can either repair it yourself or take it to a mechanic armed with the knowledge of what needs repair.
1. You have a refrigerant leak.
If you have a leak in your system, your refrigerant can slowly leak out over time. If this happens, the low pressure switch will turn off the compressor to prevent damage to other components. A full system recharge is necessary when this happens.
That may sound like a bit of trouble, but it’s actually a good thing that your AC shuts down before it causes more damage to itself, or potentially even worse damage to other parts of the car. It’s meant to be an internal safety mechanism for your AC and is doing its job correctly by shutting off when there’s too little refrigerant.
2. You have a clogged expansion valve or orifice tube.
If only your AC runs for a few minutes and then shuts off, you may have a clogged expansion valve (in newer cars) or orifice tube (in older cars).
This is one of the most common reasons why your AC could be shutting off.
Here’s how to tell if this is the problem:
The AC interferes with defrost mode, causing the windshield to fog up due to moisture in the air.
You have poor cabin heating or cooling.
Your engine will not shut off properly after turning off the ignition if you have an older car model with a clogged orifice tube. You’ll notice this because it will continue running for a few seconds after turning it off.
To fix a clogged expansion valve or orifice tube, you can use compressed air to blow through it and clear any dirt from its opening. If that doesn’t work, you’ll need to replace it. This job can be complicated and time-consuming for those without much experience working on vehicles—if that’s you, we recommend taking your car in to see a mechanic as soon as possible.
3. Your cabin air filter is blocked.
Another common culprit of your AC shutting off is a blocked cabin air filter. A cabin air filter helps to keep the air in your car clean and free of dust, pollen, and other contaminants. Ideally, it should be replaced once every year or 15,000 kilometers (9,300 miles), but this can vary depending on the make and model of your car. When you don’t replace it as often as you should, it begins to become clogged with debris that restricts airflow into the car’s air vents. This will negatively affect the overall performance of your climate control system. Check for a cabin air filter in your owner’s manual or by looking under the glove compartment—it looks like an accordion folded piece of paper.
To replace the cabin air filter:
- Take out the old one from its slot in the glove compartment
- Set aside or throw away firmly
- Open up new package
- Slip new cabin air filter into designated slot
4. Your coolant levels are low.
Coolant, also known as antifreeze, is a very important part of the cooling system in your car. It is designed to keep your engine from overheating and prevent it from freezing during winter weather. Your car needs coolant for this process to work properly.
Your vehicle will have sensors that measure the temperature of your engine and adjust the coolant flow accordingly, but if you don’t have enough coolant in there to begin with, it’s not going to be able to do its job as effectively as it should. As a result, you can experience significant problems like overheating and a damaged engine.
You might notice that there are some telltale signs of low coolant levels, including:
- Cooling system warning light comes on
- Temperature gauge rises above halfway point
- Engine overheats
If you notice any of these issues or suspect that your car may not have enough coolant in it for another reason, then we encourage you to bring your vehicle into our service center so we can take care of it for you promptly!
5. Your compressor is locked up
Lastly, your compressor might be locked up. The compressor is a heavy and complex part of the AC system–if it’s jammed, it won’t turn on. If you suspect that this is the case, check to see if the compressor clutch engages when you turn on the air conditioning. If it doesn’t engage–voila!–your compressor is broken.
This might also lead to another problem: depending on how much damage has been done, your A/C system may have lost all its oil from having run without lubrication. Your mechanic will need to add more oil and evacuate any remaining refrigerant (aka freon), then refill with fresh new refrigerant and leak test it before filling the rest of your A/C system with oil again.
There are a few potential causes to your car AC shutting off, so you should check them out and see if there’s an easy fix you can make yourself.
There are a few potential causes to your car AC shutting off, so you should check them out and see if there’s an easy fix you can make yourself. First, it’s important to check both the refrigerant levels and the coolant levels in your vehicle. If either of these are low, it can cause the AC to stop working entirely.
Next, check the compressor. If you’ve never done this before, then you might be better off taking your car to a professional mechanic who can help diagnose any problems with it for you. Similarly, if there is something wrong with the expansion valve or the cabin air filter, you’ll need a trained technician with all of their specialized tools to take care of things for you.
