Car AC Making a Hissing Noise and Not Cooling

Car ac making a hissing noise and not cooling how to fix
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The regular operation of a car air conditioner making a hissing noise shows the air conditioner is working and the surroundings are calm. Sometimes the noises can be so loud, it keeps worrying about the use of which you need to check the causes and fix them.

However, when the car air conditioner is making a hissing noise and is not cooling, you need to worry and check for what is causing the noise. Sometimes the causes can be faulty parts in the air conditioner that are not working, and you need to fix them.

Therefore, you need to check on the causes of the air conditioner hissing noise in the car. You can major on the compressor, valves, battery, and other parts that work to ensure the air conditioner maintains temperatures in the vehicle.

When the bearing is old or worn, the compressor makes some noise to check the compressor and fix them. If you are not a technician, consult a professional to help you check the causes of the hissing noise in the car’s air conditioner and improve them.

The article below shows the causes of the car air conditioner hissing noise and not cooling, meaning the air conditioner can start but cannot perform its functions; after that are the frequently asked questions and lastly, the conclusion.

How to fix the hissing noise in a car air conditioner that is not cooling

car ac making hissing noise and not cooling

1. Gather all the requirements that you need for the process

Requirements you need include the following:

2. Switch off the air conditioner

Please switch off the air conditioner for the fixing process to be more accessible by removing all the power cables.

3. Remove faulty air conditioning parts

After switching the air conditioner, you have the idea of the parts causing noise to remove the parts like condenser, compressor, and air filters and fix new parts that do not make noise. Consider calling a technician to aid with the fixing process to prevent destroying the air conditioner.

4. Align the air conditioner in place

Arrange the condenser coils in the air conditioner by ensuring they are straight to avoid loud noise production in the air conditioner.

5. Tighten the loose wires

Tightly hook the loose wires and cables in the air conditioner so that when the air conditioner vibrates, they do not contact each other and make a loud noise that destroys the owner’s comfort.

6. Clean the air filters

Remove the dirty particles in the air filters by cleaning them, picking the debris, and wiping away dust using a piece of cloth.

7. Add lubricants to the air conditioning system

Lubricate the air conditioning system to prevent corrosion that causes the motor to make screeching sounds.

Why is the car air conditioner making a hissing noise, but it is not starting?

Why is the car air conditioner making a hissing noise, but it is not starting

1. Poor capacitor battery

A capacitor has a battery that holds a charge to power the compressor and other parts in the air conditioner. Therefore if the battery is poor, it cannot store a charge that will power the air conditioner, producing loud noise as it strains to start due to lack of enough power.

2. Bad contractor

A contactor is a part of the air conditioner that regulates the connection between the air conditioning system and the power suppliers in a room. So when the contactor is faulty, it fails to perform its work by turning off or on the power supply. It forces the air conditioner to turn on the electricity itself, producing a loud noise.

3. Defective capacitor

A capacitor is a device in the air conditioning system that stores power for use by the air conditioner. Therefore, when the capacitor is loose or faulty, it prevents parts like the fan from switching on, causing noise due to friction.

4. Dirty particles in the air conditioner

The availability of dirty particles like dust, tree branches, leaves, and other debris may stick to the surface of the air conditioner.  The waste accumulates in the air conditioner blocking the air filters and producing rattling noises when exchanging air in and out of the house.

5. Old and loose screws

Old screws tend to unfix themselves from the parts they hold in the air conditioner, becoming loose. The loose screws always make loud noises in the air conditioner when starting due to the vibrations of the air conditioner making the loose screws rattle. The sudden vibration every time the air conditioners turn on makes the screws loose after some time.

6. Faulty compressor and fan

If the air conditioner makes loud noises when starting, check the fan and the compressor since faulty fans and compressors might be old enough or damaged. The compressor sometimes has leaks that make noise when the air conditioner starts as air passes through the leaks.

7. Defective connector belt

The fan and the fan motor use a connector belt to get them in touch. A defective connector belt might be because it is old and makes some noises as it expands and contracts according to the varying temperatures of the day.

8. Free and loose air filters

When the air filters are loose, the air conditioner produces a loud noise when starting because the air passes through the air filters, and if there are some loose parts, the air will pass through these parts, producing some noise.

9. Faulty electrical connectors

When starting, faulty electrical connectors like the signals and sockets may affect the air conditioner, producing loud noise since the connectors will keep switching off and on, making some noise. Deficient electrical components can cause some sparks when starting the air conditioner where noise accompanies these sparks.

10. Defective thermostats

Defective thermostats result from using the thermostat for a long time, making them poorly connected to the air conditioner. After that, the loud noise results from the relay, which keeps sending power to the faulty thermostat.

11. Dirty air filters

Dirty air filters block the exit and entrance of air into the air conditioner, making the motor produce loud noise since air forces itself into the air conditioner, which comes with high pressure. The air conditioner’s force to create a path into the air conditioner makes noise in the air conditioner.

12. Insufficient lubrication in the motor

Some motors need lubrication more frequently for fast and easy running. Therefore, when such engines lack lubrication, they will produce noise at the start, making the air conditioner have loud noise if the lubrication process fails to occur.

Frequently asked questions:

  • What are the different types of noises from the car’s air conditioner?

The different types of noises from the car’s air conditioner include the hissing sound, the clicking sound., humming noise, grounding noise, squealing noise, and others. The noises are normal, but when they turn loud, there is a problem with the air conditioner.


When a car’s air conditioner is making a hissing noise but is not turning, it shows it has some problems with the internal parts that you need to fix to curb the noise in them. The article above shows the causes in detail with the steps you can follow when selecting the noise.

Therefore consider following the steps in the article carefully to reduce the hissing noise in your car. Remember to follow the manufacturer’s instructions when trying to fix the hissing noise in the vehicle. You can choose to consult a technician to help you select the problem if you cannot do it.

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