Why Does AC Compressor Turns On And Off – How To Fix?

AC compressors are meant to be turned on and off every 20-25 minutes for a cycle. However, when the compressors start turning off and on more frequently, it’s a problem. 

It’s only supposed to turn off when the interior is cooled enough and not when the compressor wants to. Yet, the problems are often overlooked, which causes irreversible damage to your compressor, where replacing the compressor isn’t the solution either.

Nevertheless, knowing just the names of the problems won’t help you solve the issue. So read on while we cover the in-depth reasonings and solutions that also include the symptoms of each problem.

AC Compressor Turn On And Off – 6 Reasons With Fixes

If the compressor kept running for hours, you would not be able to stay in your car as it would be unbearable cold. Thus, it turns off and on to match the thermostat that you put your ideal temperature. 

When the compressor reaches the thermostat temperature, it turns off for a few minutes and turns back on when it starts to get warm again.

As mentioned before, the compressor generally turns off after 20-25 minutes. However, when this process repeats every 4-8 minutes, it’s a problem.

There are several reasons the AC compressor can turn on and off. Some common reasons behind this problem include;

• Lack of refrigerant
• Faulty compressors
• Dirty cooling fans
• Blown fuse
• A grimy cabin filter
• Electrical issues in the ECU

Nevertheless, the ones mentioned above are the most common problems where lack of refrigerant and dirty cooling fans have been the top reasons.

However, knowing the names won’t play a role if you don’t know the problem in-depth. So let’s take a deep dive into it with their solutions. 

1. Lack Of Refrigerant

This refrigerant/freon helps your car’s cabin to stay cool by flowing air through the system. Thus, any shortage of it would lead to the air being stuck in the cabin. Shortages can be caused either by prolonged used or a leak in the AC system. 

The Fix

The simple solution here is to check for leaks. If you find any greasy solution around the compressor or cabin, the refrigerant leaks. So, simply cover the leaky seals where the refrigerant is stored. 

On the other hand, the cabin may just be low on refrigerant and just needs a refill.

2. Faulty Compressors

The most common symptom of a faulty compressor is when the air conditioner blows warm air from the blower. Additionally, weird noises will be coming from it.

Compressor plays a significant role in converting warm air to cold one. So when it’s malfunctioning, the compressor may be sending the wrong signals to the system. Consequently, the compressor turns on and off.

There are numerous reasons why the compressor might be faulty. Some of the common reasons are;

• Unfit suction line size
• Debris in the system
• Refrigerator refilled too late
• Electrical problems in the vehicle system

The Fix

Well, there aren’t any particular fixes that you can apply when it comes to a faulty compressor.

The first thing you can do is take it to an HVAC car mechanic and try to ensure the old one works. If it can’t be fixed, you have to replace it. 

3. Dirty Cooling Fans-

The cooling fans are generally located in the front or back of your vehicle’s radiator. These fans play a significant role in thermal control. Unfortunately. they are prone to specks of dirt.

A dirty cooling fan will not effectively transfer heat. Therefore, a compressor malfunction is also seen.

The Fix

Simply take out the cooling fans and clean all the blades with any degreaser

Additionally, make sure you reach every corner of the fans. However, don’t get too harsh with the cleaning. Here’s a video of how to clean the cooling fans properly;

4. Blown Fuse –

Every air conditioner has a fuse installed inside it that protects the condenser from excessive voltage.

The fuse might have gotten popped due to dirty filters and loose electrical. This will cause the compressor not only to malfunction but also damage the entire air conditioning system. 

The Fix

The only fix here is to replace the fuse. However, if you are new to the field, identifying a blown fuse can get tricky.

Additionally, you don’t want to change a well-working fuse just because you don’t know how to identify it. 

Well, we have included a diagram below that will help you through the process.

5. A Grimy Cabin Filter-

The cabin filter is responsible for the ventilation in the car. With a grimy cabin filter, the airflow will be limited by dirt which will make the ventilation system of a car work harder.

Due to this, the air conditioner also has to work harder, and the output received is not sufficient, leading to the compressor’s short cycle.

The Fix

Replace the cabin filters or clean them. If it’s been too long since you haven’t changed it, make a change. Whereas, with a recently installed one, try cleaning the filter.

It’s recommended that you change the cabin filters every 30,000 miles to get optimal performance. 

6.Electrical Issues In The ECU-

Apart from other components, the ECU is also in charge when it comes to the air conditioner in your vehicle.

If anything goes wrong with the ECU, there might not be sufficient power for the air conditioner to run smoothly.

Thus, the compressor doesn’t get to run at its full potential, which results in restarting the compressor again and again.

The Fix

One of the complicated parts of your vehicle is the ECU. So it’s best if you don’t touch it. Rather, go to a professional. Show what’s going on.

Besides, let’s take a look at the symptom when there is an issue with the ECU system.

Symptoms For AC Compressor Turns On And Off Problem

Here’s a table of what you would come across for each problem listed above.

Problem	Symptoms
Lack of refrigerant	AC blowing warm air
	Visible leaks
	Hear a flash when AC is turned on
Faulty compressors	Warm air is blown from the blower
	Odd noises
	Refrigerant leak
Dirty cooling fans	Engine overheating
	Temperature warning light
Blown fuse	Some parts do not function properly
	The test light is not bright
A grimy cabin filter	Increased fan noises
	Hazy windows
	Almost no airflow from the vents
Electrical issues in the ECU	Engine misfires
	Check engine light on
	Engine surges

Frequently Asked Questions (FAQs)

Before we wrap up, let’s take a look at some frequently asked questions and answer them accordingly.

Conclusion

To conclude, there are plenty of reasons why you might come across AC compressor turns on and off. Always check up on the refrigerant level on your compressor to not run into these compressor problems often. 

On the other hand, always make sure the cooling fans are in good condition and are out of the debris.

Following these two on a daily basis will reduce the chances of these problems significantly. Yet, if you still can’t fix the problem, going to a professional is the right path to follow.