Skip the auto shop - Our mechanics make house calls

Q: The AC smells like fertilizer.

asked by on

Hello, and thanks for your help. I recently bought a 2014 Mercedes C250 with 21,500 miles on it-and everything works well, except the air conditioning smells like fertilizer for the first minute or so after I turn it on. I am in Texas, and it is really hot down here, so the problem is exacerbated. Should I replace the cabin air filter? Is there mold growing in the ventilation ducts? Did something die up there? What should I do? Again, thank you!

My car has 21500 miles.
My car has an automatic transmission.

It sounds like you have mold or mildew in the system. The most likely place for it to grow is on the evaporator itself. That component gets very cold and humidity forms condensation on it. That moisture along with heat can foster mold growth. I suggest changing the cabin air filter and having the AC evaporator cleaned. There are products available that are made to clean the unit without removing components. It comes in a spray form and creates an expanding foam that disinfects and cleans your vent tubes and evaporator. Check your local parts store for the cleaner or have a certified technician, like one from YourMechanic.com, complete the cleaning for you. Afterwards I suggest running the AC on maximum, and recirculate to remove most of the moisture from the interior of the vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Parking brake replacement.

One of two things could be causing your parking brake issue. This is either caused by parking brake shoes that have been completely worn down causing them not to grip the brake rotor enough to hold the vehicle in place...

Q: Why does my red brake light with exclamation mark show up when I start my 2004 Audi A4

Hello. This can be caused by low brake pad lining or by low brake fluid. I would usually start by checking the brake fluid level. If the fluid level is low then it will cause this light to come on....

Q: Put the key in the ignition and the car will turn on, but the steering wheel will not turn...Locked in position.

It sounds as though the locking pawl is jammed in position. Sometimes that can happen if there is a side force on the steering when the lock is engaged. If the car is parked against a curb, or if the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...