Burning Smell From A Car’s AC – Plastic and Rubber – Risks and Fixes | CarZaza (2022)

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

Burning Smell From A Car’s AC – Plastic and Rubber – Risks and Fixes | CarZaza (1)

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.

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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.

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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.

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?

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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.

(Video) weird humming sound with plastic rubber and burning smell

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.

Burning Smell From A Car’s AC – Plastic and Rubber – Risks and Fixes | CarZaza (4)

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.

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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.

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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.

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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?

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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.

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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

How do you fix burning rubber smell in car? ›

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.

What happens if you smell rubber burning? ›

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.

What can cause a burning smell in car? ›

5 Common areas that can cause a burning smell from your car: 1) the clutch - may result from riding the clutch or needing a replacement, 2) the brakes - can occur from heavy break usage or riding the brakes, 3) an electrical short, 4) the heater - may result from debris in the system or from a bad motor, or 5) burning ...

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.

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).

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.

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 the AC smell like it's burning? ›

Overheating Motor

In the inside part of your AC unit, there's a fan that moves the air around your home. The bearings in the fan can break down, causing the motor that powers the fan to overheat. If that happens, you'll smell a burning smell.

Why does my car smell like burning rubber when I accelerate? ›

If Your Car Smells Like Burnt Rubber

This may be the result of an engine belt that's slipped. It could also be a hose from the cooling or power steering system that's rubbing on a belt and has started to melt.

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 does my car smell like burning oil but no leak? ›

The oil is probably leaking down onto the hot exhaust system and burning off — leaving an odor but no drops. As long as the oil level doesn't drop below a safe level, this leak isn't harmful.

Does serpentine belt smell like burning rubber? ›

Serpentine Belt Slipping

It may be that your air conditioner compressor or power steering pulley may be locked or jammed, causing the belt to slip, creating heat and, as a result, a burning smell of rubber.

What does it mean when you smell something burning but nothing is burning? ›

Brief episodes of phantom smells or phantosmia — smelling something that's not there — can be triggered by temporal lobe seizures, epilepsy, or head trauma. Phantosmia is also associated with Alzheimer's and occasionally with the onset of a migraine.

Does smelling burnt plastic harmful? ›

The burning of plastics releases toxic gases like dioxins, furans, mercury and polychlorinated biphenyls (better known as BCPs) into the atmosphere, and poses a threat to vegetation, and human and animal health. Smoke seen rising from burning waste in Nairobi's Dandora dumpsite.

Why do I keep smelling burning plastic? ›

Phantosmia is the medical word doctors use when a person smells something that is not actually there. The smells vary from person to person but are usually unpleasant, such as burnt toast, metallic, or chemical smells. Phantosmia is also called a phantom smell or an olfactory hallucination.

How toxic is burning plastic? ›

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.

Does burnt plastic emit carbon monoxide? ›

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.

Can a dirty air filter cause a burning smell? ›

Dirty Filter

If your air filter is clogged, these contaminants can get sucked into the blower and cause it to overheat. This can also lead to dirt and dust reaching the heat exchanger and heating up. Both of these will cause a burning smell and can be mostly avoided by changing your filter regularly.

How do you know if your compressor is overheating? ›

How to Test an Overheated Compressor (Diagnosis & Causes)

What happens when compressor overheats? ›

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.

What causes a compressor to go into thermal overload? ›

An overload might open due to: A lack of maintenance. If the outdoor coil gets dirty it can raise the head pressure and make the unit run hot. A defective run or start capacitor.

What does a burning catalytic converter smell like? ›

Rotten Eggs or Sulfur

If a smell is similar to rotten eggs, this could indicate that your catalytic converter may not be properly processing hydrogen sulfide in the exhaust. Take your car to a mechanic as soon as possible.

Can you drive a car with burning smell? ›

In fact, these problems are so serious that the very next stop in your car needs to be to the mechanic. Burning smells can start fires, total engines, and take out your brakes. Get your vehicle to a mechanic or repair the underlying issue – but don't keep driving your car!

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.

What does burning transmission fluid smell like? ›

#3 Burning Smell

Fresh transmission fluid tends to smell sweet or tart. When that smell turns burnt, your transmission fluid has broken down and the system is burning too hot, leading to an increase in friction and corrosive activity in the engine.

How much does it cost to fix an engine that burns oil? ›

A car that is burning oil can come from a variety of causes. The fix to your leak can be as simply as replacing an oil filter or as complex as replacing an entire blown head gasket. On average, repair costs for a vehicle burning oil will be about $600. This average is high because of how expensive some oil repairs are.

How do you know if your engine is damaged without oil? ›

If your engine is damaged from no oil, you'll notice a lit-up oil pressure warning dash light, a burning oil smell, grinding noises, a smoking or overheating engine, and overall weaker engine performance.

Can a belt cause burning smell? ›

If the belt is worn, or if any of the pulleys are not functioning properly, this will cause the belt to slip. This slippage will result in a burning rubber smell.

How do you find the source of electrical burning smell? ›

Electrical fires tend to smell like burning plastic, so they have a telltale acrid odor. Others say the scent is reminiscent of fish. That said, electrical fires don't always produce an odor. In that case, you'd have to listen for a buzzing sound or check for a brown outlet cover.

Why do I keep smelling poop in my nose? ›

If you have, you may have experienced phantosmia—the medical name for a smell hallucination. Phantosmia odors are often foul; some people smell feces or sewage, others describe smelling smoke or chemicals. These episodes can be sparked by a loud noise or change in the flow of air entering your nostrils.

What does an electrical fire smell like? ›

An electrical fire initially has a fairly acrid smell of plastic burning. The short could be in the outlet or in the wiring inside a wall and can be hard to locate. Experts say if you smell something electrical burning you are lucky – most warning signs of electrical fires are invisible and odourless.

Why does my car smell like burning rubber when I accelerate? ›

If Your Car Smells Like Burnt Rubber

This may be the result of an engine belt that's slipped. It could also be a hose from the cooling or power steering system that's rubbing on a belt and has started to melt.

Why does my car smell hot but not overheating? ›

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.

Why does my car smell like burning oil but no leak? ›

The oil is probably leaking down onto the hot exhaust system and burning off — leaving an odor but no drops. As long as the oil level doesn't drop below a safe level, this leak isn't harmful.

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 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.

What does a burning catalytic converter smell like? ›

Rotten Eggs or Sulfur

If a smell is similar to rotten eggs, this could indicate that your catalytic converter may not be properly processing hydrogen sulfide in the exhaust. Take your car to a mechanic as soon as possible.

Can you drive a car with burning smell? ›

In fact, these problems are so serious that the very next stop in your car needs to be to the mechanic. Burning smells can start fires, total engines, and take out your brakes. Get your vehicle to a mechanic or repair the underlying issue – but don't keep driving your car!

How do u know if your heater core is bad? ›

Five Signs Your Car's Heater Core Is Going Bad
  1. Fog Inside Your Car. Two things could be going on if you have fog inside your car. ...
  2. Sweet Smells in the Car. The sweet smell in your car might not be your perfume or the donuts you're taking to work. ...
  3. Constant Engine Coolant Loss. ...
  4. Cold Air in the Cabin. ...
  5. Cold Cabin/Hot Engine.
1 Oct 2020

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.

What does burning transmission fluid smell like? ›

#3 Burning Smell

Fresh transmission fluid tends to smell sweet or tart. When that smell turns burnt, your transmission fluid has broken down and the system is burning too hot, leading to an increase in friction and corrosive activity in the engine.

How much does it cost to fix an engine that burns oil? ›

A car that is burning oil can come from a variety of causes. The fix to your leak can be as simply as replacing an oil filter or as complex as replacing an entire blown head gasket. On average, repair costs for a vehicle burning oil will be about $600. This average is high because of how expensive some oil repairs are.

How do you know if your engine is damaged without oil? ›

If your engine is damaged from no oil, you'll notice a lit-up oil pressure warning dash light, a burning oil smell, grinding noises, a smoking or overheating engine, and overall weaker engine performance.

What does a burning 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.

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 burnt motor oil smell like? ›

If Your Engine Oil Smells Like This, You Have a Serious Problem

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