Car Won’t Accelerate When AC Is On (13 Common Reasons)

You might think something is severely wrong with your car if it won’t accelerate well when the AC is on.

Here’s some information about the air conditioning problems that may occur while speeding up.

Why Your Car Won’t Accelerate When the AC Is On

Your vehicle’s AC system puts a hefty load on the engine because it has to allot some of its horsepower to it to run the compressor.

Therefore, you might notice a tad bit of sluggishness if you have a four-cylinder engine.

Also, if there’s anything else going on with your car, you’ll see more of a drag.

The following are issues that could contribute to your loss of power when you run the air conditioner:

1. Your catalytic converter is plugged.

The catalytic converter is a vital part of your exhaust system that converts harmful air pollutants into less dangerous versions. It runs very hot and is prone to getting clogged. Poor gas, dirt, and carbon buildup can contribute to the clogging.

Once this item clogs, it will no longer help with acceleration by generating power. Instead, it will cut off some of your engine’s power and cause you to lose acceleration. That problem can significantly affect your acceleration abilities with the AC on.

Typically, one of your car’s sensors will trigger the “check engine” light if you have that type of issue. Then it will be up to you or a mechanic to run a test to see where the car is faulty.

2. Your car is overheating.

Another problem that might cause your car to accelerate poorly with the AC on is a loss of coolant. A coolant leak will overheat your vehicle to the point where it becomes sluggish and then stops running.

Always keep both of your eyes on the temperature gauge so that you can see when the temperature is getting out of hand.

Refill your coolant if necessary, and then have someone examine your vehicle to find the reason for the coolant leak.

It might be an issue as minor as a worn hose or as serious as a blown head gasket.

The opposite can also happen. When a car won’t accelerate properly before warmed up.

3. You need fresh new spark plugs or wires.

Old or worn spark plugs might cause your vehicle to underperform when the AC runs. They will cause your engine to misfire, which means you won’t get power from all the cylinders.

Thus, you will notice a huge decrease in acceleration ability if your car has only four cylinders. Using the air conditioner might make it run with turtlish speed.

If you feel like taking initiative, you can lift up your hood and check the spark plugs yourself. The process will be more straightforward if you purchase a spark plug remover.

Once you get them out, you’ll need to perform a visual inspection. Look for rust, ash, or caked-up carbon and replace them if you see any of that.

4. Your fuel filter is messy.

The job of most filters is to collect nasty stuff and stop it from getting into something pure.

Thus, they eventually get dirty and need to be replaced because they lose effectiveness.

A dirty fuel filter might be bogging your engine power down more than necessary when you operate your air conditioning system. That’s likely your problem if you also notice hard starting, stalling, or a rough idle. A mechanic can change your fuel filter, but it might be pricey if it’s in a hard-to-reach place.

5. Your air filter is dirty.

The same concept is true for your air filter, which is located under the hood. It will get dirty and filmy after catching debris for so many miles.

If you pull it out and inspect it, you’ll know immediately if you need to replace it.

You’ll typically see a layer of dirt on it if it’s time to change it. Sometimes, a simple air filter swap does the trick.

6. Your throttle body is dirty.

The throttle body is responsible for the amount of air that gets into your engine.

Therefore, a defective or dirty one can cause a shortage of air and a drastic power loss.

You can take your car to a seasoned mechanic to have it professionally cleaned or purchase a cleaning spray that you can release into the air duct.

You may notice that your sluggishness issues are resolved shortly after that.

7. Your engine mounts are worn.

Drivers usually don’t think of the engine mounts when they have slow acceleration, but they can also be the culprit. When engine mounts break, they allow the vehicle to freely move and vibrate up to an entire foot.

Your car will not accelerate well if you have a broken or damaged engine mount because of excessive rotation.

You can examine your vehicle to see if your engine mount is broken.

You’ll need a second person to start your car so you can look under the hood and observe the engine’s movements.

Alternatively, you can opt to jack the car up and look underneath.

Your vehicle will need immediate attention if your engine mount is broken.

8. You have a defective condenser.

The culprit could also be a defective condenser. However, this problem should be taken care of immediately because it can cause much more harm than sluggish acceleration.

Broken condensers can cause electrical failures, engine overheating, and problems with other components. Furthermore, you might start hearing a bunch of disturbing noises.

The part’s price can range from $50 to several hundred dollars, and the labor can vary as well.

It’s a pricey fix, but it will eliminate the sluggishness while making traveling more enjoyable for all your passengers.

9. Your IAC valve is bad.

The idle air control valve is mostly responsible for ensuring that your vehicle idles when you don’t have your foot on the accelerator pedal. When it goes bad, it can cause a wealth of problems related to your power and acceleration.

The most common symptoms you may notice are fluctuating speed, stalling, slow acceleration, and freezing.

This problem can seem 10 times worse than it is when you have your AC turned on.

Professional diagnostic testing can pinpoint this issue so that you can have a mechanic replace the necessary parts. You may find that your car is no longer sluggish when you use your AC once you have the work done.

10. You have a not-so-good mass airflow sensor.

All the sensors in your car read the information and report it to the computer. The computer then signals other components to do their jobs to certain specifications.

The MAF sensor measures air density and communicates with the computer so that the car delivers gas. You will not get the proper amount of gas if the MAF sensor reads the air density improperly. Thus, you’ll need to replace it if it’s causing the problem.

A quick scan with an OBD2 scanner will tell you if you need a new MAF sensor. You can first try unplugging it and reconnecting it to see if you can overcome a random glitch.

11. You’re carrying a heavy load.

The problem is the weight if you transport heavy items or numerous people. The weight places an additional load on your car, contributing to the loss of power.

You’ll most likely notice less sluggishness after you empty the contents from your vehicle or drop your passengers off.

In that case, you have nothing to worry about, and you can continue to operate your car with the AC blasting.

12. Your gas isn’t high quality.

Bad gas can put a damper on your overall engine performance, and it can worsen when you run your AC. You have three choices when poor-quality gas is in your tank.

  • You can purchase a fuel siphon system and remove all the gas from your tank
  • or try a fuel additive and see if it helps.
  • or take it to an automotive shop to have a mechanic remove it.

13. It’s hot outside.

The temperature may play a huge role in your loss of power when the AC is on.

You could lose an additional 4 percent of your horsepower on a hot day if you have a coexisting issue, such as a failing mass airflow sensor.

It’s best to take your car in for diagnostic testing if you continue to experience a loss of acceleration when you engage your air conditioner.

The technicians at the shop can connect it to a diagnostic machine that will pinpoint the issue so that you can avoid a trial-and-error diagnosis.

Those are some common reasons your car won’t accelerate when the AC is on. The above list is not exhaustive, but you can get an idea of what might be happening to cause the issue you’re experiencing.

Remember that you’re more likely to notice sluggishness if you have a car with an older manufacture date, fewer cylinders, or less horsepower. Don’t hesitate to take your auto in for a technical diagnosis if the issue seems out of the ordinary.

Sources

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