Ac compressor won’t engage with good relay fuse but engages when using a jumper in it’s place

Ac compressor won't engage with a good relay fuse but engages when I use a jumper directly in it's place

My car has 130000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Check all ground connections in the circuit. Inspect the fuseholder itself. Although the fuse may be good, if there is too much resistance in the connection, you’ll get a voltage drop. Same holds true for the relay. In fact, relay contacts can have enough resistance to create a voltage drop. If the fuse and relay, and their contacts are all pristine, and power is leaving the relay but not making it to the clutch coil, that means the wiring to the clutch coil has a defect. You can just simply abandon the existing wiring and install a new conductor through an appropriate (safe) path and crimp on a new terminal. If you desire that a Mechanic trace the circuit and resolve this for you, using the wiring diagram in the Factory Service Manual, please request an electrical circuit/component diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

That means either pressure is too low in system, switch is faulty and providing wrong ohms. You have measured your pressure and it is not low. You have measured your switch and it is providing correct ohms. Your switch has the same ohms as the jumper that are using that does works.
What`s Preventing the A/C Compressor from Engaging? One of the reasons why compressors do not engage is because of a low pressure lockout, a poor ground, a bad clutch coil, an opening in the wire to the clutch coil, or simply a blown fuse.
If the clutch doesn`t engage, the problem could be a blown fuse, an open in the wire to the clutch coil, a bad clutch coil, a poor ground, or a low pressure lockout. In some vehicles the compressor clutch relay is turned on and off by the low pressure switch and the evaporator temperature sensor.
Faulty Air Conditioner Capacitor

The starter relay moves that power to the compressor from the capacitors. If your compressor isn`t working but the fan is,you may have a faulty capacitor. This is a common and fairly simple problem, but it`s important to leave this repair to a qualified and experienced HVAC technician.

Without enough air, compressors will stall, and yours may hum when you try to restart it. To check and see if your air filter is the cause of your air compressor humming, unscrew and remove it, then restart your machine. If it works, you need to clean your filter.
The clutch is powered after the AC is turned on. This causes the compressor drive`s armature plate and compressor belt to engage, causing the compressor drive to rotate alongside the vehicle`s engine. A friction plate and an electromagnetic coil make up the clutch.
Switches, relays and transducers control the clutch (and therefore the compressor), keeping the system operating smoothly – and, in the event of failure, shutting the compressor down to prevent catastrophic failure.
With the AC off, the clutch does not spin. When you turn the AC on, the clutch can make a momentary click and starts spinning with the belt and pulley. If the clutch does not engage, or if it makes a screeching or whining sound when it does, the compressor needs to be serviced.
Yes, this is possible. However, unless it was the AC compressor clutch and pulley which failed, bypassing the AC pulley is unnecessary. Simply disconnect the wire to the AC compressor clutch and that should do the trick.
The air conditioner (A/C) relay, is a relay used to send electrical power to the air conditioning compressor, and air conditioning compressor clutch when the system is turned on. It operates just like any other relay, and is often controlled by a button labeled `A/C`.
A relay is a switch that controls the flow of electricity to your air conditioner, allowing you to turn the air conditioner motor on and off, providing you with cold air when you need it.
Car suddenly stalls while operating: One of the most common symptoms of a failed ignition relay is a car that suddenly stalls while operating. If the ignition relay shorts, burns out, or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system.
In general, this problem is caused either by a dirty condenser and fan or a clogged condenser. The condenser unit won`t turn on: If your condenser unit won`t turn on at all, you may have a faulty motor or the unit may not be receiving power. Examine all wiring and ensure that the unit is plugged in.
When your thermostat tells your air conditioner to cool the house, the capacitor`s job is to provide two hundred forty volts to start up the compressor, fan motor, and blower motor. After the capacitor jumpstarts those parts, your A/C can begin cooling outside air and blowing it throughout your home.
Look for it first around on the exterior of your machine, especially along the bottom edge near the ground. An AC`s reset button is typically red and visible, so it should be easy to spot. If you don`t see a reset button on the outside, it could be located inside the unit behind the service panel.
Some air conditioning systems have a reset switch, which is a small, red button. Typically, the button will be on the outdoor unit. If you have a problem locating it on the outdoor unit, you may find relevant details on the equipment`s manufacturer`s manual. Press the red button for three seconds and release.
When you hear an air conditioner hard-starting, what you`re actually hearing is the compressor struggling to come on and stay on. There are a few reasons this might occur. The capacitors that send voltage to the compressor`s motor may be failing, or the compressor may have lost lubrication.
Compressor Malfunction. The compressor is one of the most important parts of your AC unit and is also one of the most common causes of loud buzzing sounds. If the compressor is not working properly, it can make a lot of noise as it tries to start up or cool down the unit.
If your car`s AC clutch keeps kicking on and off the two most common causes are low refrigerant and a faulty compressor. If the problem is low or leaky refrigerant, you must get a recharge for the Freon. Low refrigerant levels trigger the compressor`s low pressure control.
Yes, you should usually be able to rotate a car`s air conditioner compressor clutch by hand. It won`t spin around at the daintiest touch of a finger—you may need to put a modest amount of effort into it—but it should be spinning.
Listen For The A/C Clutch to Engage

If the Freon levels are too low, the clutch will fail to engage which means there`s not enough refrigerant for the compressor to pressurize. In other words, your air conditioning system has nothing to work with!

Most AC clutches are designed to spin freely when disengaged, and also with the pulley and compressor when those are engaged. If the clutch spins freely at all times, and the compressor never comes on, then it may not be engaging and therefore needs to be replaced.
Absolutely, a bad one can damage your air conditioning system, as it acts as a heat exchanger for the air conditioning unit. The engine fan keeps the condenser cool which helps to keep the convertible`s AC system running smoothly.
The compressor cannot be bypassed without the use of a compressor bypass pulley. It would cost more for a bypass for the compressor than it would be to just replace the compressor pulley. Install a new pulley or pulley bearing if it can come off of the compressor and then put on a new belt.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Ac compressor won’t engage with good relay fuse but engages when using a jumper in it’s place
ANSWER : Check all ground connections in the circuit. Inspect the fuseholder itself. Although the fuse may be good, if there is too much resistance in the connection, you’ll get a voltage drop. Same holds true for the relay. In fact, relay contacts can have enough resistance to create a voltage drop. If the fuse and relay, and their contacts are all pristine, and power is leaving the relay but not making it to the clutch coil, that means the wiring to the clutch coil has a defect. You can just simply abandon the existing wiring and install a new conductor through an appropriate (safe) path and crimp on a new terminal. If you desire that a Mechanic trace the circuit and resolve this for you, using the wiring diagram in the Factory Service Manual, please request an electrical circuit/component diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

My ac clutch is not engaging, but there is no relay in the fuse box for the ac compressor
ANSWER : If a mechanic told you only that the compressor is not "engaging" that is essentially a useless diagnostic because it is too cryptic and too vague. The compressor in the system will only operate if the compressor clutch is engaged. That clutch is electrically controlled. So, if the circuit controlling the clutch includes a relay but the relay is missing, you should replace the relay. Be sure to use the right relay with the correct electrical rating. If you are unsure if a relay is in the the circuit, you can determine what is supposed to be in the circuit by consulting the Factory Service Manual wiring diagram.

With regard to this vague diagnostic, "compressor not engaging", if the fault is the clutch simple causes for clutch failure have to be evaluated, so, in addition to a missing relay, you could have a broken wire to the clutch or maybe the clutch is bad. The clutch can often be replaced without replacing the compressor and indeed without even discharging the system (a huge plus). To get your a/c fixed at the LEAST possible cost, what you need is an intelligent, authoritative and conclusive diagnostic stating EXACTLY what is wrong and why. If you request an a/c system diagnostic YourMechanic will dispatch a certified mechanic to your location and get the system properly diagnosed and once diagnosed the mechanic will explain any required repairs. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.

2002 oldsmobile silhouette stalls and won’t start for when I use AC, but runs fine when Ac is not used
ANSWER : Hi there. In most cases when a car will not run while the AC is on, it’s due to an existing problem with the fuel or ignition system that is simply amplified. The AC is powered by a belt driven system, which draws more power from the engine in order to operate the system. In other instances, this problem can be caused by a damaged AC compressor. Due to the multiple possible sources, it’s best to have a professional mechanic come to your location and complete a car is hard to start inspection to isolate this problem and recommend the right repairs.

My cooling fan won’t turn on when I turn the ac on. Relays and fuses are good, tested the fan with the battery and it came on??
ANSWER : Hi there. In general, a situation like this occurs when either the thermostat housing or temperature sensor is not relaying the information to the fan motor to activate. However, it’s also possible that there is some electrical short within the cooling system relay’s that is causing the fan motor to not activate when it should. I think the best way to determine the precise source of this problem is to have a professional mechanic come to your location to complete an onsite inspection so they can test all systems to help isolate the root problem and recommend the right repairs.

The AC on my 2009 Altima is not working. The clutch does not engage and there is no power at the harness on the compressor.
ANSWER : Hi there. I would highly recommend having one of our professional mobile mechanics come to your location and complete an AC is not working inspection, before attempting further diagnosis. There are several possible reasons why you might be having these problems, so it’s always best to let a professional mechanic with experience in these areas diagnose the issue first.

Car won’t start batary good relay good alternator good my lights work music plays what could this be
ANSWER : Hello there. In general, when the battery is good and you have a solid power supply to accessories, more often than not the issue exists within the ignition cylinder, ignition relay or the starter / starter relay. The only way to determine this is to trace the power from each access point. If you have power upon turning the ignition switch to the starter, then the starter itself is the problem. Trace this backwards within the supply line if there is no power until you find the last point where power is supplied. If you have issues with this, you can always set up a car is hard to start inspection from one of our mobile mechanics, and they can pinpoint the source and recommend or complete the right repairs for you.

When I turn on my AC the radiator fans do not turn on. The fans do come on when the car warms up so I know they are working and the fuses are good. The AC compressor does come on and the air blows ice cold when the car is moving. Car is a 2006 Chrysler Sebring Sedan 2.7l v6.
ANSWER : The control circuit for the fans needs to be checked. For example, there is usually a condenser fan relay in the A/C electrical controls. There could be a fault with that relay and/or wiring problems, perhaps even just a loose connection, blown or loose fuse, and so forth. To resolve something like this, the recommended service is an electrical component diagnostic. If you request that diagnostic service, the responding certified mechanic will get the problem pinpointed and resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

2000 Jeep Gran Cherokee 4.0. If low and high AC pressure switches are grounding out, and clutch won’t engage, does that mean compr
ANSWER : Hello Jim, thank you for writing in. To determine what the issue is, you need to start by checking the clutch coil for full battery power (12 volts ideally). If it is, then you know clutch should engage when prompted, and you may need to replace the entire assembly. If by "grounded out" you mean that the battery voltage is shorted out and not reaching the clutch coil, then you need to find the short. If you do not have full voltage, you will need to focus on the wiring from the fuse box to the clutch coil. A clog in the system which robs the compressor of refrigerant will also cause the compressor and clutch assembly to fail. If this is the case, again you have to replace the entire assembly. For more help diagnosing and repairing the issue, contact our service department to schedule an appointment.