How to Test a Car Ac Compressor Clutch

Last Updated on June 25, 2023 by Ryan

To test a car AC compressor clutch, first park the car in a well-ventilated area and lift up the hood. Locate the AC compressor and its clutch. Connect an ohmmeter to both terminals of the connector plug on top of the compressor.

The reading should be between 0.2 – 1 Ohm; if not, then it is faulty. Check for any signs of oil leakage near or around this connection point too. If there are no leaks, apply 12 volts to one terminal while grounding other terminal with aid of jumper wire connected to negative battery post; you should see/hear engagement noise from clutch when voltage is applied which means it’s working properly and engaging appropriately as needed by air conditioning system.

  • Prepare the Vehicle: Before starting to test the compressor clutch, turn off all of the vehicle’s accessories like headlights, radio and air conditioning
  • This will help ensure a more accurate reading for testing purposes
  • Check Compressor Clutch Operation: Start up your vehicle and engage the air-conditioning system by turning it on at its highest setting (full cold)
  • Then place your hand near one of the vents in order to feel if there is any cooling airflow from inside of vent; if so, then you know that your compressor clutch is engaging properly with no problems or faulty wiring issues
  • Observe Compressor Pulley Motion: Open up your hood and take a look at the pulley located adjacent to where you saw/felt cool air coming out earlier; as long as this pulley is spinning when AC is activated, then it means that there are no problems with either electrical connections or belt tensioner itself – successful diagnosis! 4
  • Test With Multimeter: If everything looks normal visually but still suspect something may be wrong electrically then use multimeter set on ohms scale in order to check for continuity between wire terminals connected directly onto compressor clutch assembly – if readings come back within expected range (typically 0 ohms +/- 5%), then congratulations! Your car’s AC system has been successfully tested without any major issues being detected

How-to Test for AC Compressor Clutch Function

How Do I Know If My Ac Clutch Or Compressor is Bad?

If your air conditioner is not functioning properly, it may be due to a failing or damaged AC clutch or compressor. To determine if this is the cause of the issue, you should inspect both parts for signs of wear and tear. The AC compressor should be checked for any broken or bent parts, while the clutch should be inspected for any loose connections, cracks in its housing, frayed wires, and worn out bearings.

If either part is found to be faulty or damaged beyond repair then you will need to replace them with new ones. Additionally, you can use an amp meter to measure current draw on the AC system which can help diagnose problems related to low refrigerant levels as well as a bad compressor or clutch.

How Do I Manually Engage My Ac Compressor Clutch?

Engaging the compressor clutch manually requires a few simple steps. First, locate the relay switch for the AC compressor and make sure it is in the “off” position. Disconnect any power sources to ensure safety before proceeding further.

Then, remove any air intake or other components that may be obstructing access to the clutch plate on your AC compressor. Once you have complete access to the plate, use a wrench or socket set to rotate it by hand until you feel resistance from the clutch coil spring underneath. If successful, this should cause your AC compressor’s pulley wheel to spin freely when turned with another tool such as an adjustable wrench or pliers.

Make sure all connections are secure before powering up again and if necessary, add more refrigerant fluid if needed after checking its levels first.

How Do You Test a Compressor Clutch Coil?

Testing a compressor clutch coil is an important step in diagnosing and repairing air conditioning systems. The most common way to test the coil is with an ohmmeter, which measures resistance on a scale of zero to infinity. First, you should remove the power source from the system and disconnect all wiring from the compressor clutch coil.

Then place one lead of your ohmmeter on each terminal of the coil, being sure not to touch both leads together or any other part of the engine. If there is no reading at all then you have likely identified that your compressor clutch coil has failed and needs replacing. However, if there is a reading present this could indicate that coils winding have shorted out or it may mean that another component within your air conditioning system has failed instead.

Should Ac Compressor Clutch Spin Freely?

The answer to this question is generally yes, the AC compressor clutch should spin freely. The AC compressor clutch is responsible for engaging and disengaging the air conditioning system whenever it is needed. When the system isn’t running, the clutch should be able to turn smoothly and quietly without any resistance or vibration.

If there is resistance when you attempt to spin it, then it could indicate a problem with either your AC belt or your bearing assembly that needs to be addressed immediately.

How to Test a Car Ac Compressor Clutch


How to Test Ac Compressor Clutch With Multimeter

Testing an AC compressor clutch with a multimeter can help you determine if your compressor is working as expected. To do this, first disconnect the power from the AC unit and locate the two wires going to the clutch. Connect one of your multimeter’s leads to each wire then set it to measure resistance (ohms).

If you get a reading between 0-20 ohms, that indicates that the clutch coil is functioning correctly. However, any other readings will indicate an issue with the compressor and may need further investigation or repair.

How to Tell If Ac Compressor Clutch is Bad

If your AC compressor clutch is bad, you may notice strange noises coming from under the hood or a lack of cold air flowing through your vents. You might also find that the AC system is not working efficiently and takes longer than usual to cool down the cabin. To confirm whether this is caused by a faulty compressor clutch, you can check for loose parts around it or inspect it visually for signs of wear or damage.

Additionally, if you have access to an ohmmeter, testing the resistance in each coil of the compressor clutch can help determine if there are any issues with its operation.

How to Test an Ac Compressor on a Car

To test an AC compressor on a car, start by connecting the negative terminal of your battery to the positive terminal and then turn the engine over. Next, you’ll want to check for any signs of leaks in the system and inspect all of the belts and hoses for any visible damage or wear. Additionally, look at all electrical connections that are associated with the air conditioning and make sure they’re securely connected.

Once everything looks good, start up your car and set it to maximum AC level before turning off your engine again. Finally, use a pressure gauge to measure how much pressure is being produced in order for you to determine if there are any issues with your compressor’s performance.


The testing of a car AC compressor clutch is an important part of ensuring the proper functioning and maintenance of your vehicle’s air conditioning system. By using simple tools such as a multimeter, you can quickly determine if it is working correctly or not. This test should be performed regularly in order to prevent costly repairs down the line and keep your car cool during hot summer days!


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