You turn on the air conditioning in your car so you can feel an icy cold breeze, only to find your ac won’t come on. Many times, this scenario means the ac compressor clutch is not engaging. Well, the summer heat can be blazing in some places where it is certainly no time for the ac to stop working. Your car’s ac system is comprised of a few components which work together to pump cool air into the cabin. When the ac is not delivering, it’s time to find out why. Read on to find out about a common reason why your car’s ac is no longer blowing that cold air.
The Automotive AC System
The ac system in cars is designed to cool a small area while the car is moving or sitting in idle. The system is complex and relies heavily on electrical components to function. Three parts are needed to engage properly in order for the ac to work: the compressor clutch assembly, belt-driven pulley, and the ac compressor clutch (view on Amazon). The ac clutch is a very important part of the automotive ac system. The clutch regulates the status of the ac compressor.
The ac compressor pushes the ac refrigerant to the evaporator for condensing. The refrigerant is finally pushed through the lines and cooled by the radiator. You then have cold air pushed into the cabin through vents. In order to get this end result, all of the parts of the ac system must be working.
The AC Clutch
The ac compressor clutch is a part that is electromagnetic and designed for the purpose of engaging and disengaging the ac compressor pulley from the ac compressor drive. The clutch becomes energized when the ac is turned on. The compressor belt and the armature plate of the compressor drive are engaged, which causes the compressor drive to rotate along with the engine. When the ac is turned off, the clutch is de-energized and the compressor belt and the armature plate of the compressor drive are disengaged.
Causes of AC Clutch Not Engaging
A bad ac compressor clutch can really take away from the driving experience in hot temperatures. You know there is a problem when you turn the ac on MAX and you don’t hear that heavy sound of the compressor turning on. If your car’s ac does not come on when you turn it on, there is a big chance the problem is the ac compressor clutch. There are a few reasons why your ac clutch will not engage:
Corroded CAN bus harness wires – Corrosion in the CAN bus harness (view on Amazon) wires Is a very common problem that plagues the electrical wires and the connectors. The Controller Area Network (CAN bus) is the communication link between the parts in your car. The CAN bus also allows the engine communication units (ECUs) to communicate with each other by transforming r data over frames. Sensor problems arise when the CAN bus wires become open or corroded. The ac clutch is next in line for damage if the corrosion is not addressed in a timely manner.
Damaged ground wire – The ground is the foundation for the electrical wire operation. When the ground is damaged or goes bad, the electrical currents must find alternative paths to the battery. The lights inside your car may flicker randomly when the ground is damaged.
Damaged or worn clutch plate – The auto ac system relies heavily on electricity to function. The ac clutch can fail when the electromagnetic features become damaged or overheated. The clutch plate also becomes worn over time, which then causes the ac clutch to slip or to fail.
Symptoms of AC Clutch Not Engaging
The first sign of trouble in the automotive ac system is no cold air. Anything else would probably not be considered a real problem. Some cars are more prone to ac problems than others, especially older cars with antiquated parts. At any rate, the ac compressor clutch cannot be in full working order if the ac will not turn on. If you believe you have an ac compressor clutch that will not engage, read on to see if you recognize any of the symptoms:
Warning lights – Warning lights on your dash will usually activate to let you know something is wrong. You can use an OBD2 Scanner (view on Amazon) to check for trouble codes which have anything to do with the ac system.
Grinding and squeaking noises – When the ac clutch is in ill repair, you may hear loud grinding or squealing noises seemingly coming from the ac compressor. There may be a worn bearing in the middle of the problem. It may be a rattling noise if the problem is in the pulley bearings.
What to Do When the AC Clutch is Not Engaging
If you suspect that your ac clutch is not engaging, surely the next step is to find out how to fix it. There are a few approaches to fixing an ac clutch which won’t engage. A visual inspection is always a good idea when looking for problems in parts you can see when you lift the hood. Besides that, here are the most common steps to fixing the ac compressor clutch problem before taking your car to a professional:
Use a mechanic’s stethoscope probe (view on Amazon) to listen to your clutch – To use the stethoscope, turn your engine ON. Place the probe on the ac clutch in an area that is still. Turn the ac on HI. Listen for noise that may be coming from the clutch. Watch whether the ac clutch is engaging and spinning. If you hear the noise coming from the ac clutch, but the clutch is not engaging and spinning, most likely there is a short in the internal clutch. If you see a lot of movement in the clutch pulley, that means the shaft bearings could be worn out.
Clean the connections– Problems with ac clutch engagement often involve electrical issues. To check your ac system’s electrical connections, turn your engine OFF. Then, disconnect the wire connector. Try to clean the contacts of any debris or corrosion. Use paper towel or cotton with an electrical spray. After contacts are clean, turn the engine ON and turn the ac to HI. Use a jumper wire on the positive battery terminal while touching the wire to the wire connector hot wire on the clutch side at the same time. Then look to see if the ac clutch engages and spins. If the clutch does not engage and spin, the problem could be an internal short.
Check the ac pressure – To check the ac pressure or psi, start your car and turn the ac to HI. Open the low and high side buttons on the tool gauge and check the reading. The psi for the low side should be about 25 to 40. The psi for the high side should be about 200 and 225. If the gauge reads are not close to these parameters, or there is no charge, there is a problem with the ac compressor. compressor. The relay is blocking any voltage from activating the clutch. The ac must be charged up with refrigerant.
Check the refrigerant – Your car’s ac system should use either R13 or R134a refrigerant. The ac expansion valve turns the refrigerant to gas. If your ac uses R12, then hook the ac gauge hose to the low side nipple. Connect the high hose to the high side of the compressor nipple. If your car uses R134a refrigerant, then you should connect the low hose to the 13 mm compressor nipple and the high hose to the 16 mm compressor. Note: Even if you replace the refrigerant, if the ac clutch is bad, the air will still come out of the ac warm.
Tighten the ac belt tensioner pulley– The ac belt can also become damaged or go bad. The pulley connects the ac compressor clutch to the engine crankshaft so the ac compressor will come on when you turn your car on. To tighten the belt, turn your engine OFF. Examine the pulley belt for any contamination or cracks. Also, be sure to check for the correct tension. There should not be more than one quarter inch of play in the belt. If you feel play, then loosen the mount bolts at the base of the ac compressor. Then, loosen the top adjusting bolt. Pull the ac compressor against the belt until there is no longer slack. Retighten all the bolts. You can also diagnose a belt that needs replacing when you cannot defrost the windshield.
Check the evaporation coil – You can find the evaporation coil inside the cabin of your car. The air blows over the evaporation coil to cool the air off. If the coil is not working properly, you may here a hissing sound. You may also encounter a bad smell when you turn the ac on and also the heater. The evaporator coil is sometimes pretty expensive to replace; however, if it is leaking or damaged, you must replace it.
Check the seal – The shaft bearing seal could be the root of the problem. To test the seal, turn your engine OFF. Take out the bolts holding down the faceplate and remove the plate from the ac compressor clutch. Check the shaft bearing seal for residue or corrosion, such as an oil film. If there is residue, the shaft bearing seal is working properly. This means the refrigerant is being discharged from the ac system. Clean the seal and replace it. Recharge the ac system.
Replace a blown ac relay fuse – The problem could be a blown ac relay fuse. To check it out, locate the fuse box. Inside the fuse box, find the ac relay fuse. If you are not sure which one is the right one for the ac, check the fuse diagram for your fuse box. Once you find the right fuse, if the fuse is blown when you pull it, replace it. Plug in another fuse of the same amperage in its place. Then, reconnect the negative terminal cable to the battery post. Turn your car back ON and turn the ac to HI. Check to see if the ac clutch will engage and spin. If it does engage and spin, the problem was a bad fuse.
Now that you know all that there is to know about the ac compressor clutch in your car, it’s time to get a move on. Although you can drive your car without using the ac system, any problem under your hood should addressed as quickly as possible. Besides, you don’t want to miss that ice air during the summer heat. So, get it fixed and get going.