Alright so today on Repairs101 I thought I�d
talk to you about that awful funky smell coming out of your car�s air-conditioning. If you
live in a warm climate or a particularly humid climate you�re going to have a problem like
this. It arises every the first few minutes when you first start up your vehicle and you
turn on your air conditioning. The smell comes out � it smells like a wet dog or an old
pair of work socks or some sweaty guy�s work-boots� or maybe some gross old carpet.
Alright so today on Repairs101 I just thought I�d talk about how every summer somebody
asks me – what�s that awful smell coming out of the air �conditioning in their car?
It�s fairly common and it�s surprisingly easy to fix.
OK so I made this 3D cutaway model using Google�s �SketchUp� to try and help represent how
the major components of the air conditioning system are laid out in the car, more or less.
The condenser is up front. The evaporator is hanging on the firewall right in front
of the cabin. The compressor�s on the engine somewhere. And then you�ll have your expansion
valve or orifice tube located usually right in front of the evaporator.
OK now I got this image from my John Deere �Fundamentals of Service� textbook. They�re
excellent books. OK so it�s going to come into the compressor
as a low pressure gas, the low pressure gas is going to get compressed into a high pressure
gas. The high pressure gas will go into the condenser and become a high pressure liquid.
The high pressure liquid gets through an expansion valve then and becomes a low pressure liquid
which then flows into the evaporator to become a low pressure gas and in doing so becomes
exceedingly cold. The blowers blow the warm air from the cabin over top of the evaporator,
they do a heat exchange � the hot air molecules are picked up by the refrigerant and then
piped back into the compressor to start the cycle all over again.
Here�s a schematic representation. So when you turn on your A/C the blowers move
the cabin air over the evaporator and pick up a funky smell that�s the result of a
microbial growth. It�s a mould or mildew or a fungus that�s growing on the evaporator
and that�s what that smell is. If you�re blowing that smell in your face I�m afraid
you�re blowing mould in your face. Dirt and dust and organic material collect on the
evaporator as the result of getting past that intake screen. Now the evaporator itself is
a moisture magnet. So you�ve got this dust and dirt and organic matter all combining
with a very, very wet environment. So it�s the perfect breeding ground for mould.
OK so the question would be: is there anything that you can do to prevent this from happening
to your vehicle? And the answer is yes, there is actually. What you do is when you�re
out driving and you�re using your air-conditioning � just before you get to your destination,
you know, a couple of blocks � turn off the air conditioning, switch it to vent, leave
the fan on full and try to use the blower to dry the evaporator before you park your
vehicle. I�m going to use this product here, �Clean
Air�. It�s a little more expensive than just using an ordinary room deodorizer or
certainly vinegar and water would be the least expensive option. If you�re living in a
really hot and humid environment where your A/C is running Full Tilt Boogie all the time
then you�re going to be doing this quite often and you might want to just use something
inexpensive like an ordinary household disinfectant like �Lysol�. If you�re sensitive at
all to smells or chemicals you might just try a mixture of water and vinegar shot out
of a solvent sprayer like this one. (Gun sprays) (Key buzzes) (Engine shuts off) (Can squirts) (Keys jangle) (Music plays) (Engine starts) (Blowers blow) (Can squirts) (Blowers blow) (Can squirts) (Blowers blow) (Music plays)