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How Often Should A Car Ac Compressor Cycle On And Off?

How Often Should A Car Ac Compressor Cycle On And Off?

Be it the AC of your car or the one at your home; the compressor is the central unit of every air conditioning unit. It’s the one that’s responsible for the cooling effect of your ac. Now, you might have witnessed that your car’s ac compressor frequently goes on and off.

It’s called cycling, and it enables the compressor (or the AC unit) to maintain the temperature inside the cabin set on the thermostat.

Say you set a particular temperature on the thermostat. Depending upon various factors, the compressor will stay on till the cabin temperature reaches the temperature set by you. As soon as the temperature increases, i.e., the air becomes hotter, the compressor will restart and follow the same pattern. But how often should the compressor go on and off? Let’s find out.

How often should a car AC compressor cycle on and off?

As said above, the cycle time of a typical car AC compressor depends upon various factors. These include the condition of the compressor, the temperature outside, the temperature on the thermostat, and so on.

Your standard AC compressor would cycle for about 15-20 minutes before going off. Or it’s 2-3 times in an hour.

If the cycle time of your ac compressor isn’t this, you should not worry much as long as the compressor doesn’t stop at all. It is because the continuous running of an ac compressor shortens its life span and requires the help of an HVAC technician.

Why Does The AC Compressor Cycle On And Off?

While it is normal for an ac compressor to cycle on and off, it may resort to short cycling in case of certain faults. In simple words, when your car’s ac compressor isn’t completing one full cycle of cooling, it’s called short cycling.

Short cycling leads to poor cooling of the cabin and puts extra pressure on the air conditioning unit. Short cycling often impacts the internal mechanism of the air conditioner.

But why is my car’s ac compressor short-cycling? Here are some popular reasons to check out.

The thermostat is faulty

The thermostat is the device that senses the temperature of the cabin or surroundings and sends signals to the AC accordingly. Thus, if the thermostat itself is faulty, it’ll send wrong information to the air conditioner and lead to its weird cycling.

Hence, check the thermostat for its condition and, if needed, try repairing it by replacing its batteries.

The air filter is dirty

Is your air filter dirty? If yes, it’s the culprit in this case. When the air filter is dirty or clogged up, it restricts airflow to the AC system and gives rise to many problems, including frequent on and off.

Thus, ensure that your car’s ac air filters are clean and open.

Frozen evaporator coils

Although frozen evaporator coils result from mechanical problems, they can also happen if you run your AC in the winter months. As a solution, completely shut the entire system down and allow it to thaw.

If the evaporator coils start to freeze again, get the ac unit professionally checked.

Low refrigerant levels

Due to leaks, the refrigerant will escape from the ac unit, and its shortage will make the compressor work overtime to cool down your cabin space. If continued for long, it will lead to malfunctions, one of which is short cycling.

Certain electrical issues

If everything else seems fine, including the temperature outside, thermostat, and refrigerant levels, and still the compressor is short cycling, there is an issue with electrical connections.

As a solution, get your car’s ac system checked professionally for faults.

So, these are the common reasons why a car’s ac compressor short cycles.

Does the car AC compressor run all the time?

No, as discussed above, the car ac compressor doesn’t run all the time and cycles on and off frequently. In case your car’s ac compressor runs all the time, here are the possible reasons.

Auto climate control

In modern cars, there is an additional feature called auto climate control. As its name suggests, it automatically controls the temperature of your cabin space. It often leads to your car’s compressor doing overtime in cooling down the cabin.

Thus, you’ll find your compressor running all the time.

Low refrigerant

If the refrigerant is present in a low amount in the reservoir, the compressor will find running the ac. Due to this, it will have to work harder than usual and keep running.

Dirty air filter or evaporator coils

If any of these seem dirty or clogged up, the ac compressor will have to keep running to cool down the air to the desired temperature.

So, these are the top reasons why your car’s ac compressor might keep running, although it should not run continuously. If the compressor doesn’t cycle on and off as it should, it’d shorten its lifespan and also impact its performance in the long run.

What’s the actual function Of An AC Compressor?

The compressor is the main functional unit of your car’s ac unit, without which it can’t produce cool air inside the cabin. As soon as you push the ac button(s), you activate this main compressor unit.

It then compresses the refrigerant (a gas) and heats it to a temperature. This heated refrigerant then passes through the condenser unit to cool down the air.

Note that the heated refrigerant may contain contaminants. The filtered out refrigerant enters the expansion valve, thus completing the compression cycle. It also passes through the dryer, where all the contaminants get removed.

The cool air you receive from the AC vents or blowers is due to the cold refrigerant present in the compressor tank. So, that’s how your air compressor works or the actual function of the compressor unit.

What to do if your AC compressor cycle on and off weirdly?

Now that you know what is causing your ac compressor to cycle on and off weirdly, here are some common fixes.

  • If the air filter is dirty, get it checked, cleaned, or replaced if the former two do not work.
  • If the refrigerant level is an issue, check if it’s low and top it to its optimal levels.
  • The compressor’s condition is also vital. Thus, check whether the compressor is working fine or not.
  • If there is an issue with the thermostat, make sure to check its battery. If battery replacement doesn’t work, you may need to replace the thermostat unit.

There can be other solutions as well that will depend upon what is exactly causing the problem.


A standard car ac compressor cycles on and off about 2-3 times an hour or for about 15-20 minutes. It helps it to work properly and cool down the cabin air.

However, there may be chances that the compressor will either short cycle or keep running all the time. In both cases, you should get the compressor unit checked for faults that are causing such issues.