Can Air Conditioning Affect Transmission?

Car air conditioning does not directly affect transmission if the system is working properly. However, overheating from a malfunctioning car A/C can break down transmission fluid, leading to jerky shifting of the transmission. Engaging the A/C compressor also puts extra load on the engine, potentially causing rough shifting. If engine RPM is limited with A/C on, the vehicle may be in ‘limp mode’ and check engine light may also come on. Proper car A/C maintenance helps avoid transmission issues.

Have you been worried that your air conditioning unit may have an effect on your transmission? You’re not alone. In fact, many vehicle owners have concerns about the impact of the air conditioning on their transmission, and rightfully so. 

You can also read my guide on transmission shifting hard when cold.

How Does Car Air Conditioning Consume Power?

car ac system and its clutch working

Simply put, the AC compressor clutch is the link between the engine and the air conditioning system, transferring power from the engine to the AC compressor. It’s responsible for engaging and disengaging the AC compressor when the AC is turned on and off.

When the ac is turned on, the ac compressor clutch engages, transferring power to the ac compressor, which then powers the air conditioning system. 

AC compressor has a pulley that gets power from the engine’s crankshaft via a serpentine belt. AC compressor clutch engages with that pulley to run the AC compressor. You can read more in my guide on ac compressor engages intermittently.

The amount of power consumed by the ac compressor depends on several factors, including the size of the car and its engine, the size of the ac compressor, and the condition of the ac components.

When the compressor is engaged, it puts extra load on the engine, reducing its overall power. This is why your car’s engine will feel sluggish and may even struggle to accelerate when the AC compressor is engaged.

How Can Air Conditioning Affect Transmission?

Air conditioning can affect a vehicle’s transmission in the following ways:

1. Cooling System Is Compromised

transmission cooler lines

Transmission fluid, after lubricating the components of the transmission, passes through the transmission cooler lines to maintain its temperature. You’ll find transmission cooler lines near the radiator.

In some cars like Dodge, the radiator and transmission cooler are separate components. In other cars, transmission fluid exchanges heat through the lower portion of the radiator.

If the engine starts overheating while the AC is on, transmission fluid will not be able to exchange its heat properly with the coolant flowing through the radiator. This is because the temperature of the engine’s coolant will not be lowered.

As a result, transmission fluid will break down and lose its hydraulic properties. Furthermore, engine overheating will also damage the engine’s components and the proper functioning of the engine’s sensors which are responsible for efficient engine operation.

You should monitor your vehicle’s dashboard. If it shows that the temperature of your vehicle’s engine is increasing while the AC is on, you should immediately stop the vehicle and find the causes of engine overheating.

2. Bad Transmission Fluid

If transmission fluid has broken down due to overheating of the engine, it will lose its viscosity and lubrication properties.

You need to check the color of the transmission fluid. A healthy transmission fluid has a reddish tint. So, if your transmission fluid is brown or black, it means that transmission needs to be flushed

3. Engine Is Rough Idling and Stalling

Engine stalling and rough idling occurs when the engine is not receiving the right amount of fuel or air. This can cause the engine to suddenly stop running or it can cause it to run roughly, vibrating and jerking as it does so.

The engine may also start and stop in rapid succession, and it will not respond to the accelerator when you press it.

When the engine is running rough or stalling, it can cause the transmission to shudder and not accelerate as smoothly as it should. This can make you feel like the transmission is malfunctioning when it is actually the engine that is the problem. 

So, when you turn on the car AC, the AC compressor can consume 5 to 15% of the engine’s power, which reduces the power to drive the vehicle. If your engine stalls or rough idles, turning on the AC will worsen the condition and make your vehicle jerky. This will make you feel like your car AC is affecting the transmission.

Furthermore, if the engine is running rough or revving on its own, it will eventually damage the transmission as well.

Now let me explain why it does happen…

The transmission fluid pump runs mechanically from the engine’s power. There is no electrical connection to the transmission oil pump.

So, the higher the engine’s RPMs, the more transmission fluid is pumped through the transmission.

If the engine’s RPM is fluctuating due to rough idle when AC is on, transmission oil will not be efficiently pumped through the transmission components and cooling system. This will cause increased wear and tear on the transmission, resulting in increased maintenance and repair costs.

4. Malfunctioning AC Compressor

The AC compressor is a critical component of the AC system as it helps to circulate the refrigerant and maintain the correct pressure. 

When the AC is turned on, the compressor is activated, drawing power from the engine.  When the compressor isn’t working properly, it can put extra strain on the transmission, causing it to slip and lose power.

This can be especially problematic when the AC is on and the compressor is working hard to keep the car cool.

If the AC compressor is partially seizing, it could drag the engine and transmission down, and cause wear and tear. Your car may feel like it is slipping or jerking when it shifts gears. 

You can watch the below Youtube video to check if the AC compressor of your car is seizing:

5. Reduced Engine Power Mode

If the vehicle is in reduced power mode, your vehicle will not smoothly shift into higher gears when you turn on the AC. 

Reduced engine power mode or ‘limp mode’ is a safety feature that’s designed to protect your engine and transmission from damage when there is any serious problem with the engine.

When it’s triggered, the engine cuts power to the transmission, reducing the amount of power sent to the wheels. This is done to prevent overloading, which can cause serious damage. 

What Are The Symptoms Of A Bad AC Compressor?

Here are the symptoms of a bad AC compressor:

Bad Smell

One of the most common signs of a malfunctioning compressor is a bad smell coming from the vents. If you smell something odd or unpleasant, it could be a sign that the compressor is having issues. 

Warm or Hot Air

Another common sign of a malfunctioning compressor is warm or hot air coming from the vents. If the air coming out of your vents is not cold, it could be an indication that something is wrong with the compressor.

Noisy Air Conditioner

If you hear a loud, grinding noise coming from your air conditioner, it could be an indication that the compressor is having issues. If the noise is coming from the compressor, it’s likely a sign that it needs to be replaced.

Leaking Fluid

If you see fluid (refrigerant) leaking from your car’s AC system, it could be an indication that the compressor is malfunctioning. If this is the case, it’s important to get it fixed as soon as possible because the fluid can affect other parts of the system.

Damaged Serpentine Belt

A malfunctioning AC compressor will also cause the serpentine belt to wear out faster. If the serpentine belt shows signs of glazing or similar effects of heat caused by the belt having to work harder, the chances are that your vehicle’s A/C compressor is seizing. The serpentine belt may begin to lose its strength and elasticity, or it may even melt from all the chaffing and rubbing. 

The damaged serpentine belt does not directly impact the acceleration of your vehicle. However, the serpentine belt is responsible for running the vehicle’s accessories like the water pump, alternator, etc. So, if the serpentine belt is severely damaged, it will not properly run a water pump, due to which the engine might start overheating.

Furthermore, if the alternator does not run due to bad serpentine belt, it will not charge your vehicle’s battery. If the car battery is low on charge, your engine sensors will not work properly

What Are The Causes Of Engine Rough Idling?

Here are the causes of engine rough idling:

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