When The AC Compressor Refuses To Turn On: Troubleshooting Tips


    The AC may not be critical to your car’s operation, but it is vital to your comfort when you’re driving. If you’re getting hot air through your AC vents, there are many different culprits. One of which could be the AC compressor. Learn more about your car’s AC system to help you diagnose problems to make the best decisions to take care of your car.

    What Does the Compressor Do?

    The air conditioner takes outside air and pushes it through its system to cool the air before coming out in the vents. As the outside air moves through the refrigerant, the refrigerant absorbs the heat. Once that refrigerant can’t take in any more heat, it needs to be pushed out of the way for new refrigerant to continue to do the work. The AC compressor circulates the refrigerant that cools the air. Although you can certainly drive your car without the AC compressor, it won’t be a comfortable ride.

    Check the Thermostat Settings

    When your AC doesn’t work, the most obvious thing is to check the setting. If the thermostat is set higher than you thought, the car won’t produce cold air. While is the easiest fix, if you still aren’t getting cold air, it might be a problem with the refrigerant. A slow, small leak can go unnoticed until it’s empty. Low refrigerant can cause the AC compressor to not click on. You can’t use a car clip to fix this.

    Listen for Unusual Noises

    The AC compressor may make weird noises when it’s bad. It can sound like chattering, whining or even chirping. You may hear these noises when you engage the AC switch or you may hear them when you run the car. The culprit could be a faulty compressor, but it could also be due to a faulty clutch. You should hear the clutch switch on and start spinning when you turn the AC on. If you don’t hear a click before the clutch starts spinning, it could be the compressor. You need AC service.

    Check the Battery

    The compressor runs off the electricity created by the alternator and battery. If the compressor doesn’t get enough voltage from the battery, it won’t turn on. If you notice that other electrical components in your car aren’t operating well, this could be the right fix. Use a multimeter to measure the car’s battery voltage. If it’s below 12 volts, your battery may be failing. You may need to replace the battery instead of components in the AC. You may also want to check the alternator.

    Replace the Compressor

    If adding more refrigerant to your car’s AC system doesn’t work, your compressor may simply be dead. It could also just be a switch or other component, but you should consider the worst-case scenario. Replacing the compressor won’t be as expensive as replacing the entire AC system, but it may not be a DIY project. Make sure you feel confident before taking any parts off your car.

    Shop for all the parts you need to take care of your car, from an O2 sensor to an AC compressor