Your car’s coolant has a 1:1 mixture of antifreeze and water. The antifreeze is mixed with water to reduce its freezing point and increase the boiling point. It has a sweet smell, which you might sometimes experience after turning the AC on.
So, why is the antifreeze smell coming through the vents? The main suspect is a leaked heater core. It is a crucial part of the cooling system, and a leaked heater core will cause an antifreeze smell through the vents. Other reasons include faulty radiator caps, leaked coolant hose, and more.
Let’s talk about the reasons in detail and find fixes to this problem.
Antifreeze Smell Coming Through Vents: Detailed Reasons and Solutions
Take a closer look at the reasons and utilize the fixes to solve this issue.
1. Heater Core Is Leaked
When you turn the car’s engine on, it starts to heat up. The coolant flows around the engine and absorbs the heat from the engine. It then flows through the cooling system to the radiator and the heater core. The heater core uses heat from the coolant to increase the cabin temperature.
If there are internal leaks in the heater core, coolant will reach the cabin vents. When you turn the AC on, the air coming through the vents will have an antifreeze smell. You might also experience coolant loss with the AC on. The heater core can leak if old coolant flows through it.
Old coolant doesn’t have enough corrosion inhibitors, so they can’t protect the inside of the heater core.
Solutions
1. If an antifreeze smell is coming out of the vents, you should turn the AC off and roll the windows down. Breathing the antifreeze vapor isn’t good for you. When the smell is only from the vents without any other symptoms, the heater core is faulty.
2. Try to seal the heater core using a sealer. You can use the K-Seal Coolant Leak Repair to seal the heater core. This product is easy to use and can temporarily seal the heater core to prevent the antifreeze smell.
3. Drive to a car repair shop as soon as possible and get the heater core checked by an experienced mechanic. You should get the leaks fixed or the heater core replaced, depending on the condition. It will cost about $500-700, including parts and labor costs.
2. Faulty Radiator Cap
The pressure cap on the radiator maintains a specific pressure inside the cooling system. There can be two types of faults with the pressure cap. The pressure in the coolant system when cold can be 4 psi to 30 psi, depending on the car type.
If you are using a pressure cap with the wrong high-pressure specifications, it may increase the pressure inside the cooling system. As a result, the coolant hoses may crack, and the coolant can leak through them.
Sometimes, the pressure cap may have a low-pressure specification or the O-ring under the cap can be broken. In that case, coolant vapor will leak through the radiator pressure cap.
The smell of antifreeze can then get into the cabin air intake ducts. So, you will experience the antifreeze smell from the vents.
Solutions
1. You should pull the car over and turn the engine off. Open all doors and let the antifreeze vapor escape. Wait until the engine is cool.
2. Check the radiator cap pressure specifications on the label and match it with the vehicle’s manual. Both pressures should be the same. If you are using the wrong pressure cap, change it.
3. Open the cap and check the O-ring under the cap. If it is cracked or broken, replace it.
4. Visually inspect the coolant hoses for signs of leaks or cracks. If there are any, replace the leaked hoses to prevent coolant leaks.
3. Coolant Reservoir Is Damaged
When the coolant gets hot, it expands and takes up more space in the system. The coolant reservoir is designed to provide that additional space. So, the hot coolant will flow into the reservoir or overflow tank.
If there is a hole in the coolant reservoir, the coolant can leak from the reservoir. A leak on the reservoir cap can also cause the leak.
The vapor from the leaked coolant will then get into the air duct and mix with the air entering the car’s cabin. So, you will get the antifreeze smell from the air vents. It is a sweet, syrupy smell that you can distinguish right away.
Solutions
1. You should turn the car off and let it cool down. Then, pop the hood.
2. Check the coolant reservoir and the cap for signs of leaks or damage. It is a translucent plastic container at the back of the engine bay. If there are minor cracks, you can temporarily seal them with coolant reservoir sealers.
3. But it doesn’t guarantee an effective solution. The best option is to replace the coolant reservoir. It may cost about $250-300, including parts and labor.
4. Leaked Head Gaskets
The head gasket in your engine prevents the coolant from mixing with the oil. If the gasket is leaked or cracked, coolant will leak into the combustion chamber. It will burn inside the engine and release white smoke from the exhaust with a sweet smell.
Sometimes, the leaked coolant vapor can spread around the engine bay and get into the cabin air ducts. It will cause an antifreeze smell.
Solutions
You should take the car to a repair shop and get the head gasket checked. Even if the cracks are minor, it is better to replace the head gasket. It will cost about $1,000-1,500, including parts and labor costs.
Things You Should Do If Antifreeze Smell Is Coming Through Vents
Take this as a general guideline for the antifreeze smell problem and use these steps.
- Whenever you get an antifreeze smell through the vents, you should turn the AC off. If it is essential, you can select the recirculation mode.
- Keep an eye on the engine temperature gauge. Antifreeze smells indicate coolant leaks and that will quickly cause the engine to overheat.
- After fixing or replacing faulty components, don’t forget to check the coolant level and refill it.
People Also Ask
Here, the answers to some commonly asked questions may be helpful for you regarding the antifreeze smell coming through vents issue.
What happens if I breathe air with antifreeze smells?
Antifreeze vapor is bad for your health. It may cause irritations in your eyes and in the respiratory tract. So, you should be careful about it.
Why does my car smell like antifreeze but not overheating?
Even if there is a minor crack in the cooling system, the coolant vapor can escape the system and reach the cabin. But the coolant loss won’t be enough for engine overheating.
Final Thoughts
Your senses give many indications about your car’s problems. For example, when you get the antifreeze smell coming through vents, it means the heater core may be leaked. The radiator cap, coolant reservoir, etc., can also be faulty.
In such cases, you should take prompt steps to eliminate the smell and diagnose the reason. I mentioned detailed reasons and step-by-step solutions to help you throughout the process. Use them as required.
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