It’s not unusual to have smells coming through your car’s air vents when the AC is on. Often it’ll be a vinegar or a musty smell, but sometimes a burning smell makes an appearance.
It’s a smell that causes drivers to worry about whether their car is safe to drive and whether it will catch fire.
This article will explore the causes, whether they are dangerous, and the costs of putting it right.
In brief though
A burning rubber smell indicates loose hoses rubbing against the engine. A burning plastic smell means electrical components are overheating, and a burning oil smell indicates an oil leak.
As you see, the smell isn’t always AC-related but originates from the engine area before being pumped into the car cabin through the vents.
Let’s group the smells into three distinct categories. These are the main ways that people who smell burning describe them.
- Burning rubber
- Burning plastic
- Burning oil
BURNING RUBBER SMELL
AC compressor is faulty.
You’ll find your car’s AC compressor near the front of the engine with the rest of the belt-driven components.
The aircon compressor is powered by a belt that attaches to the engine. It’ll turn millions of times in its lifetime but can become frayed and brittle near the end of its life. It can come into contact with the engine when it gets to this state and burns.
A more common problem with the air compressor is when the clutch becomes stuck and won’t allow the belt to turn. This can cause friction and give off a burning smell too.
Belt pulleys, when working correctly, keep the belt tight and running accurately to the crank and back to the compressor. If this is broken or misaligned, it will often cause the belt to rub against metal too.
All faults connected to the AC compressor can give off a rubber-burning smell, and these do work their way into the car cabin through the vents.
How to fix this
You won’t need many tools to change an AC belt or replace a pulley, but if the fault is with the compressor clutch, you’ll need to get inside the clutch itself as it’s housed there.
Most people will take their car to the car shop if they suspect the compressor clutch is defective. Do it early though as often the clutch can be replaced. If it’s left too long, then the whole compressor can be damaged beyond repair.
An AC compressor clutch costs between $24 and $100 for the part and between $150 and $250 in labor. Expect to pay a total price of between $175 and $350.
See AlsoCambodia Crime. Safety and crime information on Cambodia | CountryReportsPlastic Model Kits, airplane models, boat models, car models for sale from Revell, Monogram, Aurora, Tamiya, Hasegawa and more.15 best free Android apps available right nowAIRTEL की Call Details कैसे निकाले? (2023 में कॉल History निकाले) - Pgrip
A brand new aircon compressor costs from $700 to $1,200 depending on the make and model of the car you drive.
Rubber Hoses are Loose
There are meters of rubber hosing under the hood of your car. If one becomes disconnected, it can come into contact with a hot engine or exhaust system. It won’t take long for it to start smoldering, and the rubber smell will find its way into your car’s cabin when the vents are open.
How to fix this.
You’ll need to open the hood and have a good look inside the engine bay. You may see smoke – but not always – coming from the offending rubber hose. Go around all the hoses and scrutinize the connections. Are they loose?
If they’re not in contact with the engine now you’ve stopped, could they touch it when the engine is vibrating as you’re driving?Can you see burn marks on any of the hoses?
If you find any damaged hoses, replace them and ensure they are more securely clipped in place. If needed, buy new hose clips too.
This is a job that you may feel you can do yourself. Rubber hoses are very cheap, and the clips only cost a few dollars too.
A mechanic shouldn’t charge you more than $100, including parts and labor to put things right if you’d rather a professional make the repair.
Burning Out Clutch (Manual cars only)
All smells from under the hood will find their way into your cabin through the vents. Some though, you’ll only smell in certain circumstances.
A burning clutch – not the air compressor clutch – occurs more often when you are driving slowly in a line of traffic, especially if you are in a line on an incline.
Every time you push the clutch pedal in these circumstances and engage a gear, your clutch is asked to work more often and harder. This can cause a burning smell if your clutch is near the end of its life.
The smell would disperse into the air outside the car if you were driving at any speed, but when stationary, it will find its way into the vents.
Fitting a new clutch is normally the job of experienced DIY mechanics or professionals.
A new clutch will cost between $200 and $400 for the part and another $200 to $300 for the fitting. The price difference depends on the make and model of the car and the hourly labor rate charge.
BURNING PLASTIC SMELL
There are two causes of your car’s AC smelling like burning plastic.
A build-up of dust particles
If you’ve just turned your AC on for the first time in a few months, the smell might be caused by a build-up of dust. Strange to think dust could smell like burning plastic, but some people report this.
If dust is the cause, it will only last a very short time before fading. Should the smell remain more than 30 seconds, it’s very unlikely to be a dust issue.
Electrical burning
Your car’s systems run off electric power from the alternator and the battery. Occasionally the wiring going to and from the electrical components shorts.
This means the circuit is broken, and wires or the electrical motor or valve to which the power is running can get heated.
Sometimes the smell can be powerful and overpowering. On rare occasions, the fault can lead to electrical fires, which will give off toxic fumes.
If you smell burning plastic in your cabin, it’s time to get your car inspected by a mechanic. It could be something straightforward to fix, like having a new section of wire to be fitted.
However, the burning smell could be an early warning signal that your car suffers from a major electrical problem.
It’s difficult to estimate the cost of a repair as it depends on the part – if any – that needs replacing and the number of labor hours needed to make the fix.
Overworked Alternator
Your car’s alternator provides all the electrical energy your car needs when the engine is running. It’s a big undertaking, and when they go wrong, they get hot can give off a burning smell.
If the small is like burning rubber, then the alternator serpentine belt could be loose and rubbing.
If it’s a plastic burning smell, it is more likely caused by the bearings inside the alternator or the cables going to your battery from the alternator. You’ll probably hear a grinding noise too.
How to fix this.
If you’ve discounted a dust buildup and damaged wires or shorting out, it could be the alternator is overheating.
As we’ve discussed, any burning smell in the engine area will find its way through the AC system and into the cabin.
A mechanic will be able to diagnose an alternator fault by running a few tests with a multimeter.
An alternator can often be rebuilt, but sometimes a car shop will send them away to a specialist to do this.
As a general rule brand new alternator will cost from $175 to $350. Labor costs range from $200 to $400 so expect to pay between $375 and $750 in total.
BURNING OIL
Of course, your car’s AC isn’t powered by the engine or the oil within it, so why is burning oil on the list, you may ask.
As you’ve seen, most of the smells coming through the vents are not caused by the AC system. The AC is picking up the smells from other areas of your car and transporting them into your cabin.
Diagnosing burning oil is the easiest of the three burning smells you may come across. It can sometimes get compared to a gas smell but oil smells less sweet.
Open the hood and have a look inside. Have you or a mechanic just changed or topped up the oil?
The car’s engine gets very hot, and just a small amount of oil on it can cause it to smoke and burn.
Other areas to look at are around the oil filter, and the gasket, which keeps the top half, and the bottom half of your engine secured tightly. Is there any leaking here?
Oil can drip onto the exhaust manifold of your car as well.
Other fluids under the hood could also give a burning oil smell.
If you can’t see any obvious oil leak, then check the transmission fluid reservoir – not manual – the brake fluid and power steering fluid too. If hot, these will smell like burning oil.
How To fix
Unfortunately, the repair can be as simple as a loose hose allowing fluid to escape to a more involved and costly job such as replacing a gasket cover. The cost of repair will vary greatly too.
In Summary
The burning smell from your car’s AC is unlikely to be caused by your car’s AC. The AC transports the burning smell into your cabin.
The burning smells are grouped closely into Plastic, Oil (or fluid), and Rubber burning smells, so it’s fairly easy to discount the majority of the causes before you even start diagnosis.
Always get a mechanic to check over your car as soon as you can. A burning smell is never a good smell. Your cars got oil, gasoline, and electrical cables galore running through it.
The sooner it’s diagnosed and fixed, the safer you’ll be and the cheaper the cost of the repair will be too.
How to diagnose vinegar smells from your car AC
How to diagnose musty and moldy smells from a car’s AC
FAQs
Can I drive my car if it smells like burning plastic? ›
If Your Car Smells Like Burning Plastic
What to do: Pull over safely. If the problem is a bag or some other plastic on the exhaust, don't grab it, as it's likely very hot. If you can't locate the smell, or it persists, take your vehicle in for diagnosis and repair.
Sometimes, a burning rubber smell could be coming from an oil or fluid leak, or even a damaged or worn out drive belt. If you smell burning rubber, head to your nearest Firestone Complete Auto Care for diagnosis and expert engine repair. Loose belts and hoses don't get better with time.
Why does my car air conditioner smell like burning plastic? ›Issue #4: Electrical issues
Your AC system's electrical wiring typically has a plastic coating around it. Anything from worn electrical connections to faulty breakers/short circuits can cause the plastic coating on wires to melt, which can result in a burning plastic smell.
Normally burning occurs when two surfaces are rubbing together. If you notice any engine smells, then stop driving your car immediately.
Is burnt rubber smell harmful? ›Inhaling burning rubber or plastic is harmful as it may contain chemicals and poisons, such as carbon monoxide and cyanide. Inhaling harmful smoke from rubber can irritate the lungs and airway, causing them to become swollen and blocked.
How long does it take for burnt plastic smell to go away? ›Air out the house immediately after the plastic is removed from the heat source by opening up all windows and leaving until the smoke and the majority of fumes have dissipated (at least an hour).
How do you fix a AC compressor that overheats? ›If the air filter is clogged, air circulation suffers, the AC struggles to cool the house, and the AC may overheat. The solution is to clean or replace the air filters regularly. Apart from air filters, vents and registers also contribute to proper air circulation.
Why does my AC smell like burning rubber? ›Overheated Belt-Drive Motor
If your air conditioning system is equipped with a belt-drive blower and not a direct-drive blower, make sure it is not already wearing out. Belt-drive blowers have a rubber belt that can wear out after a few years, causing a burning rubber smell.
Cost Of Replacement Of Home AC Compressor
Generally, the cost of a home AC compressor is around $1,200. The cost to replace it ranges between $800 and $2,800. The labor and material make up around 50 percent of the final bill. The cost of its parts ranges from $450 to $1,500.
The most common reasons behind burning car smells include oil leaks, clutch/belt slippage, clogged vents, and defective engine components. Other causes stem from premature wear and tear or a disregard for proper vehicle care and maintenance. In some cases, however, driving habits are to blame.
How do you get rid of burnt rubber smell? ›
White vinegar, baking soda, fresh coffee grounds, and activated charcoal are all excellent examples of odor-absorbing products that can be placed in the bowls. Fill the bowls and let them sit in the affected area for a few hours or even overnight if the smell is fairly strong.
What does an overheating AC compressor smell like? ›#5 - The Belt Drive Motor is Overheating
This might be causing the problem if: The burning smell from AC unit smells like burning rubber. Some AC units have belt drives that power their blowers, and over time, the rubber belt drives can become worn down or even begin to melt.
The belts that power the dethatcher mechanism are made of rubber, and this smell indicates that there is stress on the belts causing them to melt while the engine is running. If the belts are too loose, they can slip off of the pulleys or have the drive pulley that powers them spin without actually turning the belt.
How long does a burnt clutch smell last? ›The smell goes away after around 2 minutes.
What does a burnt clutch smell like? ›It might smell similar to burning brakes, but has been described as a sickly, heavy stench. Some people have related it to sulphur or gun smoke. In order to avoid the costly mistake of overusing your clutch and ultimately ruining it, avoid slipping the clutch, riding the clutch or hauling a heavy load.
What is the effect of burning plastic and rubber? ›Impacts of Smoke from Burning Trash and Plastic
The toxic chemicals released during burning include nitrogen oxides, sulfur dioxide, volatile organic chemicals (VOCs) and polycyclic organic matter (POMs). Burning plastic and treated wood also releases heavy metals and toxic chemicals, such as dioxin.
Burning plastic releases a variety of noxious chemicals into the atmosphere. When burned, many plastics (particularly polyvinylchloride, or PVC) release carbon monoxide and the deadly poison named tetrachloro-dibenzo-dioxin, a toxic organic chemical that is a known carcinogen.
Are plastic fumes toxic? ›Health hazards
Plastics fume, produced when the material is heated in processing, can include respiratory sensitisers, irritants and carcinogens. The exact composition of any fume varies. Immediate effects may include severe irritation to the eyes, nose and lungs.
When plastic is burned, it releases dangerous chemicals such as hydrochloric acid, sulfur dioxide, dioxins, furans and heavy metals, as well as particulates. These emissions are known to cause respiratory ailments and stress human immune systems, and they're potentially carcinogenic.
Is burning plastic toxic to breathe? ›Smoke inhalation means you breathed in smoke from burning materials and gases. The smoke may contain chemicals or poisons, such as carbon monoxide and cyanide. The harmful chemicals may come from burning rubber, coal, plastic, or electrical wiring.
What does a burning plastic smell mean? ›
Plastic Burning Smell in House
Faulty wiring or an overheated appliance can have an odor that smells like burning plastic. If it's coming from your HVAC system, it could be from an overheated blower motor -- possibly due to heavy dust buildup or a clogged air filter.
If you have an overheating compressor in your central A/C or heat pump, it might still cool your home temporarily. But if the overheating continues or gets worse, it will result in a potentially expensive system breakdown. Having to replace the compressor is among the most expensive fixes for a central A/C.
How do you know if your compressor is overheating? ›How to Test an Overheated Compressor (Diagnosis & Causes)
Can a bad AC compressor cause car to overheat? ›Can a Bad AC Compressor Cause My Car to Overheat? The compressor itself cannot cause the vehicle to get overheated. However, if the compressor clutch is engaged but the compressor is dragging to function properly, the extra strain on the engine can cause your car to overheat.
Is it worth replacing compressor in car? ›The compressor only needs to be replaced if it fails. They can last the lifetime of the car, but generally a compressor's life span is around 10-12 years and 150 to 200K miles.
What is the lifespan of an air conditioner compressor? ›The short answer is that your AC compressor and refrigerant should last about 12-15 years. Learning what crucial components, and how to maintain the compressor, can keep your AC running efficiently for its entire lifespan.
How long should an AC compressor last in a car? ›Compressors generally last the lifetime of a car, or approximately 12 to 15+ years depending on how well the car is looked after. In saying that, it's important that you regularly check up on and service your car to prevent premature failure. Some ways you can tell if something is failing can include: Leaks.
Why does my car smell hot but not overheating? ›You likely have a small oil leak on the valve cover, or another place that is leaking on the exhaust. Also, if the smell is sweet, like antifeeze, you may have a small coolant leak as well. Lastly, check smell the wheels to see if the brakes are the source of the smell.
Why is my car smoking under the hood and smells like it's burning? ›The most common cause of smoke under the hood is small amounts of motor oil or other fluids accidentally spilled or leaking from a bad gasket or seal onto a hot engine or the exhaust system. Those other fluids may include engine coolant, power steering, brake and transmission fluid, even window washer solvent.
How long does a burnt clutch smell last? ›The smell goes away after around 2 minutes.
Why do I smell burning plastic? ›
If your house smells of burning plastic, take caution. The smell of burning plastic could be a sign of an overheated household appliance, a kitchen accident, or a problem with the HVAC system. Heaters and furnaces may smell of burnt plastic when their parts are broken or worn out.
What does an overheated engine smell like? ›You smell funny odors like burning rubber, scorched oil or boiling water. At one time, expecting your car to overheat was a common event. No one forgot extra water on a Sunday drive, as pouring it over the radiator helped the engine cool.
How do u know if your heater core is bad? ›- Fog Inside Your Car. Two things could be going on if you have fog inside your car. ...
- Sweet Smells in the Car. The sweet smell in your car might not be your perfume or the donuts you're taking to work. ...
- Constant Engine Coolant Loss. ...
- Cold Air in the Cabin. ...
- Cold Cabin/Hot Engine.
A sweet smell in a car is usually associated with engine coolant. Engine coolant is treated ethylene glycol, which smells sweet. If you notice the smell in your car, there's most likely a coolant leak, which can be caused by the engine overheating and/or having other performance issues.
Is it bad to drive a car that burns oil? ›While it's normal for some cars to burn more oil than others, it's best to have your vehicle serviced as soon as possible if you experience consistently low levels. Losing too much oil can lead to serious engine damage and expensive repairs, especially among older cars with 100,000 miles or more on the odometer.
Why is there smoke coming out of my AC in my car? ›If the air temperature near the unit is below the dew point, this causes water vapor to form in the air and condense into water droplets, thus causing the fog or smoke. A dirty air filter or low fan speed may aggravate the condition.
Can I drive my car if it's smoking? ›It could be overheating, and if it is, you need to stop driving as soon as you can. You could end up seriously damaging your vehicle if you choose to just ignore it. If the smoke smells sweet, then there is an issue with your coolant. But if it smells like fuel, there might be an issue with your fuel system.
How long can you drive with a burnt clutch? ›You can make it hours, days, or even weeks sometimes when your clutch just starts slipping. But if your car's clutch begins to slip when you're driving in higher gears – say, gear three and up – it's not long until it's going to leave you stranded.
What does a burning transmission smell like? ›Burning Smell
If you notice the odor of burning plastic, smoke, or melting wires, this could indicate that your transmission is overheating or that the transmission fluid is burning. Worst case scenario, this smell could lead to an electrical fire, which is incredibly dangerous for you and other drivers on the road.
The average cost can be anywhere from $500 to $1,000 for most cars, although it can easily go higher. So, read along as we're going to spend some time taking a look at clutch replacement costs, and how it may be replaced.