Why Is There White Smoke From My Hood When The AC Is On?

Why Is There White Smoke From My Hood When The AC Is On?

Driving can be equal parts thrilling and troubling. Trouble usually comes when you least expect it and it may be frightening. For example, it is hot outside and all you want is your AC to keep you cool as you move from one location to another; so why is there white smoke coming from your hood?

The main reason smoke erupts from the hood of a car while the AC is in use is when there is a problem with the AC compressor clutch or the compressor itself. Any wear, tear or leak in these structures or the fluids that they interact with can lead to friction and burn.

This article aims to explore the reasons for smoke erupting from a car. I look at smoke under the hood without overheating, the smoke under the hood when the AC is on, and smoke coming out of the AC vents in a car. In conclusion, I discuss ways to fix the issues with smoke under the hood.

Why Is My Car Smoking Under The Hood But Not Overheating?

Why Is There White Smoke From My Hood When The AC Is On?

Smoke under the hood of your car doesn’t mean there is a fire. You don’t have to call the fire service in a panic. Although overheating often accompanies smoke from the hood, there are situations where the smoke comes without overheating. They are:

  1. Simple condensation – water that builds up under the hood can burn off once you drive. The smoke is usually white and odorless.
  1. A coolant leak – this smoke is like water vapor, white, and has a sweet smell. It happens when coolant fluid goes into the overflow tank or drops on the engine.
  2. The oil filler cap – releases a small wisp of smoke if there’s burnt fuel within the engine. It can also happen if the PVC tubes are clogged or the piston rings are worn out.
  1. An oil spill – the smoke is white and smells like burnt tar or asphalt. It comes from oil that leaks onto the engine or burns inside the engine. A bad gasket or seal is usually the culprit.
  1. Smoke from the alternator’s copper wires being burnt. It has a pungent chemical smell.

Whatever the cause may be, do a proper check and have it fixed as soon as possible in order to avoid further damage to the car’s components.

Why Is There White Smoke From My Hood When The AC Is On?

Getting from point A to point B may not require air conditioning, but it certainly enhances the experience. A fully functional AC in sweltering temperatures gives you rest of mind. If there’s a problem with the AC system, it manifests in several ways. One of them is smoke coming from under the hood of your car, probably with a burning smell.

The Importance Of The Compressor Clutch

The compressor clutch is responsible for moving power from your engine to the pulley attached to your AC compressor. The transferred power makes the entire AC system run and at the end of the process, you get cooled inside your car. 

Your AC uses up a lot of power when you run it and if it stays on all the time, your fuel finishes and your engine wears out fast. A working clutch makes sure your AC system turns on only when you want it to.

If the AC compressor is the heart of your car’s AC unit, the compressor clutch is the pacemaker that causes the heart to beat. A leaking compressor or broken clutch can contribute to the white smoke coming from your hood when the AC is on.

Is It Normal For Smoke To Come Out Of AC Vents In A Car?

Why Is There White Smoke From My Hood When The AC Is On?

It is not unusual for smoke to come out of your AC vent. If it is odorless, you have little to worry about because it’s vapor or steam. It usually occurs when airflow hits accumulated water (from condensation) at the bottom of the heater box. 

It may point to a restriction in the drain hole that needs cleaning. You can clean it yourself by running the fan continuously to dry out the system. An alternative is to pay for it to be cleaned for about $45.

If it is smoke/steam and it has a sweet smell, then you should worry. There may be a coolant leak (pinhole) in your heater core. If the pinhole is in your evaporator core, you may see a spray of refrigerant (fine mist) from the vents.

How To Fix The Issue With Smoke Under The Hood

The first thing to do when you see smoke under the hood of your car is to pull over. Once it is safe to pull over, do so and prepare to check the hood for the source of the problem.

If you know your way around a car and it is safe to check it out, then you can try to assess the damage. Call for roadside help immediately, especially if you don’t know your way around a car.

If the car is overheating, the indicators on the dashboard will inform you. Do not pop the hood until the engine has cooled down. If the car is not overheating, then it could be simple condensation, an oil leak, or an electrical problem amongst others. 

There are some issues you can address without needing immediate help. For example, you can wait for your engine to cool down before checking for fluids. You can top up any depleted fluid just to get you to your destination.

If you notice a puddle forming on the ground or fluids dripping under the hood, it would be best to call a tow truck. Attempting to drive in that condition could lead to expensive and extensive damages.

Once your mechanic has assessed the damage, solutions will be proffered. They may have to replace your AC compressor clutch, recharge your entire AC system, fix any leaks, or change a broken gasket or seal. 

The extent of the damage determines how much the repairs would cost. To avoid being stranded on the roadside, conduct frequent maintenance checks on your car.

Gui Hadlich

Hey there! I'm Gui. To be honest, I'm not really that interested in cars. But what I'm really, really not interest in is spending lots of money fixing my car up. Thankfully, I have a father-in-law who's obsessed with cars and a brother getting a PhD in internal combustion engines, so I get to learn about fixing cars. And with Fixing Engines, I hope to help you save a lot of money and take good care of your cars.

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