Why Does My Car’s Air Conditioning Smell Weird?

Why Does My Car’s Air Conditioning Smell Weird?

Car's Air Conditioning, Cabin Air Filter, Leaking Coolant, Low Engine OilFor many of us across the country, the weather has fluctuated between hot, cool, wet, and windy – sometimes all on the same day! These temperature differences can be challenging when selecting your outfit for the day, but your car may also experience some issues. Using your car’s air conditioning intermittently may result in a weird smell inside the cabin. A few common causes include a dirty cabin air filter, leaking coolant, and low engine oil. Below, we explore the where, what, and why of these causes to help you narrow down your specific issue.

Where Does The Air In My Car’s Air Conditioning Come From?

Depending on your car’s design, outside air comes through various vents in and around your engine compartment. Air enters your car’s cabin through the heating, ventilation, and air conditioning (HVAC) system.

Possible Causes For Weird Smells

While each person may describe smells a little differently, most of us can identify an unusual odor inside our car. After sitting unused for a while, your car’s air conditioning can smell a little weird for the first few minutes. This is pretty normal. However, a prolonged, unpleasant odor may indicate an issue that requires your attention. Here are a few problems that will cause a weird smell inside your car:

  • Dirty Cabin Air Filter: Odor can be musty, dusty, or swampy (think dirty fish tank)
  • Leaking Coolant: Odor may be sweet or syrupy 
  • Low Engine Oil: Odor can be burnt or petroleum-based

What Is A Cabin Air Filter?

A cabin air filter removes dust, pollen, bacteria, and other contaminants in the ventilation system. Its primary purpose is to filter the air coming into the vehicle’s cabin through the vents or whenever your car’s air conditioning or heater is running. 


Auto manufacturers recommend changing it every 12,000 to 15,000 miles. However, if you notice a weird smell in your car or your allergies spike when you run the air conditioning, it’s time to replace the cabin filter.

Where Is My Cabin Air Filter?

A cabin air filter (or air conditioner filter) may be inside the car in the glove box or under the dashboard. Alternatively, it may be under the hood on the vehicle’s passenger side. 

Benefits Of A Clean Cabin Air Filter

The cabin air filter is prone to clogging with pollen, dirt, and other dry particulates. Also, moisture can seep into the filter material and grow mold. As you can imagine, replacing a dirty cabin air filter has many benefits, such as:

  • Fewer allergens inside the car
  • Clean & fresh smelling air
  • Increased airflow from the vents
  • Colder air from the air conditioner

What Is Auto Coolant?

Auto coolant is a protective fluid (50% antifreeze/50% distilled water) in your vehicle’s cooling system. It contains chemical additives that absorb heat, provide lubrication, and prevent rust, scale build-up, and corrosion within the engine and cooling system. 

Is Leaking Coolant Bad?

The short answer is yes: leaking coolant is bad for you and your car. Not only is antifreeze toxic, but low coolant levels can foul up your car’s air conditioning, create issues with your cooling system, and wreak your engine. 

  • If you see a puddle of coolant on the floor mat inside your car, schedule an HVAC service immediately. 
  • If you see coolant pooling under your car, clean up the spill and try to find the source. Top off the low fluid level and bring your vehicle to your auto service center for a cooling system diagnostic service right away.

What Is Engine Oil?

Engine oil lubricates vital engine components and helps prevent excessive wear. Over time, the heat-absorbing and lubricating properties in oil break down. Once this happens, the boiling temperature of your engine oil lowers, so it degrades faster. Some vehicles go through oil quicker than others, especially those using conventional engine oils. 

What Causes Low Engine Oil?

Normal wear and tear and leaks cause low engine oil levels. Routine oil changes help prevent those conditions, and all auto manufacturers highly recommend them. Of course, problems can happen unexpectedly between service appointments. Here’s a quick list of possible causes for low engine oil:

  • Bad oil pressure sensor
  • Clogged crankcase ventilation
  • Cracked oil pans or gaskets
  • Damaged head gasket
  • Faulty crankshaft or camshaft seals
  • Failing oil cooler
  • Incorrect installations of gaskets
  • Old rings or valve seals

Auto Diagnostic Service in Midland, MI

If you are looking for honest and reliable Midland auto repairs, All A’s Automotive‘s team of experienced mechanics is here to help! If your car’s air conditioning smells weird, we will determine whether a dirty cabin air filter, leaking coolant, or low engine oil is to blame. We will repair your vehicle quickly, and you’ll be on your way again soon.

Schedule Your Car’s Air Conditioning Service

Call the team at All A’s Automotive at (989)631-4672 or visit our website to schedule your appointment today!

Posted in: A/C

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