Is your car’s AC compressor stuck in overdrive? If it’s running constantly, even when the air is cold enough, you’ve got a problem that needs attention. If it’s not because of the weather, then car AC compressor stays on all the time means there is something wrong with the unit.
It should be noted that the compressor has the second-highest failure rate among all the components of the air conditioning system. Learn the possible reasons for AC compressors staying on all the time and how to troubleshoot this common maintenance issue.
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What Does An AC Compressor Do?
The compressor is the component that powers the air conditioning unit.
When you turn on the air conditioner, the compressor compresses and heats the refrigerant, a special mixture of fluid. This compressed and hot refrigerant is then sent through the condenser to cool down.
The refrigerant then goes through the dryer to get rid of contaminants. Once purified, the compressed refrigerant passes through the expansion valve, where it is stripped of its pressure. After traveling through the evaporator, the refrigerant is now super clean, dry, and cold.
To create the gusts of cold air blowing out of your car’s AC, air is sent through the newly cold refrigerant in the compressor tank to cool down and then blown out through the blowers.
Why Does An AC Compressor ‘Cycle’ On And Off?
It is normal for your car’s AC compressor to cycle on and off. For instance, hot hotter days, the cooler you set your AC, the more the compressor has to work to maintain the desired temperature.
Once the desired temperature is achieved, the AC compressor may cycle off for a while until there is a change in your car’s temperature. Thus the air conditioning system cycling on and off is not a problem, but the frequency of cycling might indicate problems.
An example of such abnormal cycling frequency is that instead of cycling on and off, the AC compressor stays on all the time.
Car AC Compressor Stays On All The Time – Common Causes
Auto-climate control
If you have auto-climate control on, the AC compressor will run continuously, summer and winter, if the auto-climate control is on any setting other than off.
Low refrigerant level
If the amount of refrigerant in the AC compressor reservoir is reduced, most likely due to a leak in the coils, the compressor might not have enough refrigerant to effectively run the AC. Due to this inefficiency, the AC compressor will have to work harder than usual.
In this case, you’ll likely need a professional to find and repair the leak and restore the refrigerant to the correct level.
Detecting leaks
Leaks most commonly occur in worn O-rings, seals, and hoses of the air conditioning system, followed by leaks in a pinhole of the condenser and evaporator, and leaks in the compressor shaft seal.
To detect leaks, add refrigerant to restore it to the correct level, then turn the AC on. The simplest but effective method is to spray soapy water on suspected areas and watch for bubbles.
If a leak occurs in the O-rings, seals, or hoses, simply having them replaced will solve the problem. However, if the issue lies with a leaking condenser or evaporator or the compressor shaft seal, the repair is expensive and more troublesome, which should be performed by a professional.
Dirty or blocked condenser
A condenser full of dirt and debris will not work as effectively as normal to cool down the compressed and hot refrigerant that passes through, resulting in the AC compressor having to overwork.
Dirty evaporator coil
Similar to the condenser, the evaporator coil may be covered with dirt and debris, impeding its drying process and the system’s overall cooling process, thus making the AC compressor work harder to cool your car’s interior.
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Repair Options
Depending on the diagnosis, repair options may include:
- Refrigerant recharge: If low refrigerant is the culprit, a recharge will likely solve the problem.
- Replacing faulty components: Pressure switches, relays, or even the compressor itself may need replacement.
- Professional diagnosis and repair: For complex issues or if you’re unsure about the cause, it’s best to consult a qualified mechanic.
How Much To Replace An AC Compressor?
If you are encountering issues with your AC compressor without knowing exactly the reason, it’s best to have it serviced. Only EPA-certified mechanics may service mobile air conditioner systems.
You might wonder how much the replacement costs for an AC compressor. The average cost for an AC compressor replacement is between $500 and $700, depending on the particular car. The labor costs alone are estimated to be just over $200.
Rest assured, an AC compressor usually lasts for 8-10 years, which is typically how long an average car owner keeps the car for.
Final Thoughts
By understanding the basics of your AC system and knowing the common culprits behind a continuously running compressor, such as low refrigerant, faulty pressure switches, or a blocked condenser, you’re better equipped to diagnose the issue and seek the right solution. Don’t let a stubborn AC compressor ruin your summer drives – get it checked out and enjoy the cool comfort you deserve!
