If your AC clutch is not engaging in your car, this article is for you. We shall discuss the AC compressor, AC clutch, and problems related to the two components. Several possibilities can lead to AC compressor clutch failure.
They range from simple to more complicated reasons. Once you read this article, you will be able to diagnose and know the reason behind the failure.
You will also learn how to jump AC compressor clutch to prevent you from getting into sudden AC compressor clutch failures.
What Is An AC Compressor Clutch?
An air-conditioning unit in a car is made up of 5 main components: the compressor, condenser, expansion valve, evaporator, and receiver drier.
The compressor is located in the engine compartment and is belt-driven by the engine. And an AC compressor clutch is a device that allows the compressor to engage and disengage from the engine.
When the clutch is engaged, the compressor will turn on and start compressing the refrigerator. And when the compressor turns off, it also means that the clutch is disengaged.
In most cases, the AC compressor clutch is controlled by an electromagnetic coil. When current flows through the coil, it will create a magnetic field, it will pull the clutch plate toward the pulley.
The AC compressor clutch is a small part with the same size as a silver dollar and in most cars, this part is positioned at the front of the compressor.
How Does An Car AC Unit Work?
An air-conditioning unit in a car is made up of five main components: the compressor, condenser, expansion valve, evaporator, and receiver drier. The compressor is located in the engine compartment and is belt-driven by the engine.
The other four components are located in the passenger compartment. The refrigerant enters the compressor as a low-pressure gas and is compressed to high pressure.
The high-pressure gas then flows into the condenser, which is located next to the radiator. The heat from the radiator causes the refrigerant to change from a gas to a liquid.
The liquid refrigerant then flows into the expansion valve, where it expands back to a gas. This change in the state allows the liquid to absorb a lot of heat from the air in the passenger compartment.
The gas refrigerant then flows into the evaporator, which is located in the dash. The gas absorbs more heat from the air and changes back to a liquid. The liquid refrigerant then flows into the receiver drier and back to the compressor, where the cycle starts over again.
Where is the AC Compressor Clutch Located?
The AC compressor clutch is generally located at the front of the AC compressor. The AC compressor is typically connected to the engine by a belt and is located at the front of the engine, near the bottom of the engine compartment.
The compressor clutch is a small, circular device positioned on the front of the compressor that is normally about the size of a silver dollar.
When the compressor belt is taken off, the front of the compressor can be seen, where a single bolt or snap ring typically holds it in place.
The clutch engages and starts spinning when the air conditioner is turned on. However, depending on the make and model of the vehicle, the exact location of the compressor clutch may vary.
It is advised that you refer to the vehicle’s service manual for detailed instructions on where to find the compressor clutch on your particular vehicle.
Signs That Your Car’s AC Compressor Clutch Is Defective
#1. Higher Cabin Temperature.
The most common sign of a damaged compressor clutch is a greater cabin temperature than usual on hot days when the air conditioner is needed.
A damaged compressor is likely to blame when the cabin temperature rises abruptly. Because the compressor is unable to control the refrigerant flow due to a damaged clutch, it malfunctions.
#2. Very Loud Noises.
It’s possible that a compressor is failing if you switch on the air conditioner and hear a loud noise. The compressor, like the engine, has multiple moving parts.
Noises are a typical issue when the clutch or another moving part begins to fail or seize. A stretched or leaking bearing, on the other hand, might produce a high-pitched shrieking sound. A stuck bearing, on the other hand, will make a grinding noise.
Because determining which element of the compressor has failed is so difficult, it’s often better to replace the complete compressor rather than try to repair it.
#3. Fluid Leaking.
The bearings within the compressor can be destroyed if the compressor clutch fails. Fluid leaking into the front seal as a result of a failing compressor clutch is uncommon, but it does happen. Examine the compressor for signs of liquid escaping from the front seal.
What Causes AC Clutch Not to Engage?
Below are some of the things that could be causing your AC compressor clutch not to engage:
#1. Incorrect Amount of Refrigerant.
The proper amount of refrigerant is required for the air conditioning system to function. Although the issue could be brought on by either too little or too much refrigerant.
The modern system utilizes an AC pressure switch lockout mechanism to protect the valuable components if the refrigerant level isn’t correct.
However, the power provided to the AC compressor clutch will be cut off, and the clutch will not engage if the pressure in the AC system is too high or too low on either the low-pressure side or the high-pressure side.
Although the AC refrigerant system may have been overfilled by you or another person if the AC pressure is excessive. if the pressure is abnormally low, the AC system is certainly leaking.
#2. Damaged or Worn Clutch.
It might just be that the AC compressor clutch has worn out, just like any other clutch, and needs to be replaced. Older cars or those that have overused their air conditioning system are more likely to experience this issue.
When the clutch is newer, it won’t typically wear out. The clutch might not engage if the clutch plate is worn out.
However, it might occasionally slip, causing operations to be irregular. Some spacer shims in AC clutches can be removed in order to give the clutch a little bit more life.
It might possibly be the result of a clutch coil failure, in which case the clutch coil won’t engage at all.
#3. Failed high or low AC pressure switch.
Another thing that could be the reason behind your AC compressor clutch not engaging is a failed high or low AC pressure switch. The AC system has two AC pressure switches: one on the high-pressure side and one on the low-pressure side.
These switches regulate the pressure to prevent it from going too high or too low. Even if the pressure is correct, a malfunctioning sensor may send the wrong signal to the AC compressor clutch and cause it to shut down. You should also learn about Engine Lubrication System with this detailed guide!
#4. Bad electrical connection.
The electrical connections and wiring in your car’s AC system are many. The clutch could stop functioning if there is an issue with any of them.
The 12V+ power wire to the AC clutch is the most crucial connection; if the wire is corroded or damaged in any way, the clutch won’t engage.
#5. Blown Fuse.
AC compressor clutch not engaging can also be a result of a blown fuse. The compressor may get too much voltage if there is an electrical fault in the AC system. The fuse will blow as a result of this operation.
It is better for the fuse to blow than for the system to receive too much voltage. If it occurred, the pricey AC components might suffer significant damage. The fuse for the AC clutch can be found by checking your owner’s manual.
#6. The faulty or leaking evaporator coil.
The evaporator coil is a component of the car’s air conditioning system that aids in airflow to cool the vehicle. Thus, if the coil is faulty or leaking, it could result in the AC compressor clutch not engaging.
When the heat and air conditioning are turned on, a hissing sound or bad odor indicates that the evaporator coil is faulty or leaking.
The clutch will not engage as a result. You might need to swap out the evaporator coil to resolve the problem. But keep in mind that replacing something costs a lot of money.
How to Examine the AC Compressor Clutch?
Using low-quality oil could be a reason for failing AC compressor clutch but it could happen even if you use synthetic oil and high-quality coolant. In a few cases, the clutch does not engage due to a clogged refrigerant circuit.
If you want to diagnose an AC compressor clutch for defects, apply these techniques.
Working method 1
Set all air conditioning controls to the MAX before kicking off the engine. Check the front side of the clutch to examine its condition. Also, find out whether the clutch and the pulley are spinning.
If only the pulley is rotating, the compressor clutch is having an issue, which could be stemming from several sources – a blown fuse, bad clutch oil, low-pressure lockout, or an open wire in the oil.
Working method 2
Before starting the next step of diagnosis, you should know that a low-pressure switch can create problems with the compressor clutch’s relay in some car models.
The system’s computer keeps the relay grounded but it can go on and off due to the bad switch. A careful inspection of the system and its components will help you to pinpoint the source of trouble.
In this step, you have to detach the connector cable from the clutch oil. Keep it safe away from all other components. Use a digital voltmeter to measure the ground and voltage of the battery at the detached connector cable.
Go on to check the fuse if you cannot read the voltage readings. Move on to the clutch relay if the fuse turns out fine.
Working method 3
In a few car models, the power of the air conditioning system flows from the AC switch to the fuse before being transmitted to the clutch oil through the low-pressure evaporator temperature.
You have to make sure that the compressor has enough oil to function properly. When you are sure that there is a problem with the clutch, the next part is to engage it. The next section tells you how to manually engage AC compressor clutch at home.
Note that: Sometimes, your AC compressor clutch can get stuck, it’s usually caused by a lack of lubrication or a problem with an electromagnetic coil.
When the clutch is stuck, it will make the compressor not disengage from the pulley and the consequence will be the AC compressor stays on all the time and the refrigerant accumulates.
How to Jump AC Compressor Clutch?
#1. Disconnect Clutch Oil Cable.
As we discussed what can make the clutch not engage properly, one of them was high/low oil pressure switches that prevent the compressor from being damaged due to bad operating conditions.
Therefore, to check whether the compressor has gone bad or not, disconnect its connector cable from other parts.
Using a voltammeter, connect it to the connector and measure the battery voltage and the ground. If there are no readings, then you need to check the AC relay and fuse.
#2. Make Sure the Compressor Have Sufficient Oil.
One of the mandatory checks before engaging the clutch manually is the presence of a certain level of oil in the AC compressor.
This can be seen from the glass display in the compressor. Check the correct level by making it above the red line. If the oil is insufficient, add some oil with the same specs as the user manual states.
#3. Set the Amount of Refrigerant.
The AC compressor should have a certain amount of refrigerant that meets the manufacturer’s requirements. This makes the ideal load on the internal compressor parts and prevents them from damage.
Measure the refrigerant with the pressure gauge installed on the high-pressure and low-pressure rail of the AC. Compare it with the recommended value and tries to balance them.
#4. Jump Start the Clutch.
After making all the above checks, you need to know how to engage the clutch manually. At the compressor’s front side, unplug the single wire connector; attach a jumper wire to the wire you just disconnected from the compressor.
Attach the other jumper’s end to the car battery’s positive terminal, and it will help the compressor start manually.
Common Mistakes While Jump Starting an AC Compressor
While jump-starting an AC compressor isn’t rocket science, there are still plenty of things that can go wrong if you’re not careful. Here are some common mistakes and how to avoid them.
Avoiding Damage to the Compressor
One wrong move, and you could end up damaging your compressor. That’s why it’s crucial to follow the steps carefully and double-check everything before turning the power back on. This isn’t a speed race, take your time.
Incorrect Wiring
Incorrect wiring is a common mistake that can lead to serious damage. Always make sure you’ve connected the wires correctly. And if you’re unsure, it’s better to ask for help than risk damaging your AC unit.
Skipping Safety Precautions
Safety should always come first. Don’t skip on safety gear or ignore water leaks. Remember, it’s better to be safe than sorry. Electricity is not something to be taken lightly.
Overloading the Compressor
Lastly, don’t overload your compressor. If it’s not starting, it’s for a reason. Continually trying to jump-start it could lead to more damage. If it doesn’t work after a few tries, call in a professional.
FAQs.
Q: How Do You Manually Engage the AC Compressor Clutch?
If the AC compressor clutch doesn’t engage automatically when turning on the AC switch in the car AC panel, you need to check the refrigerator and compressor oil levels.
At the compressor’s front side, unplug the single wire connector, take a jumper wire and attach it to the wire that you just disconnected from the compressor.
Connect the other end of the jumper’s wire to the positive terminal of the car battery. This will enable the compressor to start manually.
Q: How Do I Know If My AC Clutch Relay Is Bad?
Several indicators may help you to know when the AC clutch relay is bad. The most obvious sign of a bad AC clutch relay is that the AC compressor is not turning ON. Normally, you will hear a click sound when the clutch is connected.
If you fail to hear this clicking sound, it is an indicator that the compressor is not getting enough power as a result of a failed relay.
Another sign of a failed clutch relay is if there is no air coming out from the AC. If the clutch relay goes bad, the compressor fails to operate, preventing the AC from producing cold air.
Q: Should AC Compressor Clutch Spin Freely?
The AC compressor clutch can spin freely when fully disengaged. It will also spin freely when the compressor and the pulley are engaged.
However, if the AC compressor clutch spins freely every time and the compressor fails to turn on, it is an indicator that it is not engaging and it requires replacement.
Q: Will My AC Clutch Engage With Low Freon?
No, the AC clutch will not engage when the Freon is empty or low. The low-pressure switch will prevent the AC clutch from being engaged, and the compressor will not spin. This prevents the compressor from engaging.
The major reason the Freon is low would be due to leakage. Once you refill the Freon, check for any leakages to prevent the problem from reoccurring.
Final Words
Diagnosing what is happening in your compressor is not a hard task. All you have to do is to follow the inspection steps, and you will understand its cause.
In case you get confused, do not hesitate to reach the nearest mechanic or expert to get your car fixed, for this will save you cost and time.
It is recommendable to make a periodic inspection on the compressor oil and the refrigerator level to prevent yourself from getting into problems.