One Hundred Degrees of Separation

I’d like you to close your eyes and go on a journey with me. *cue harp music* Well, I guess you can’t actually close your eyes AND go on a journey with me, because you can’t read with your eyes closed…*a record scratches and the harp music stops*

Take 2: I’d like you to pretend your eyes are closed and go on a journey with me. *cue harp music again* You’ve been working out in the hot triple-digit weather ALL DAY LONG. You’re hot, sweaty, and dreaming of the sweet, sweet relief of the ice cold air conditioning in your car on your trip home. You tremble with excitement as you open your car door. You start the engine, squeal with joy, and…nothing happens. Cold air does not bestow itself upon you. You realize that you are doomed to a torturous ride home. You begin to weep.

Scary, isn’t it?

For many people, the air conditioning system in their vehicle is one of the most treasured modern luxuries. What kind of technological sorcery makes the cold air happen? What are some common problems with these systems? How does one prevent and solve these problems? I intend to shed some light on those questions with my information lamp.

See what I did there?

See what I did there?


The basic idea behind an air conditioning system is that it condenses high pressure, high temperature vapor to liquid. That is evaporated into low pressure, low temperature vapor (which makes the cold that is blown into the passenger compartment!). That is compressed back into high pressure, high temperature vapor, and the process starts all over again. To help illustrate this, here’s my buddy, Freon:

Poor Freon. He just wants to enjoy the breeze!

Poor Freon. He just wants to enjoy the breeze!

Just so you know what drives all of this, here’s the terminology for the major components:

  • First of all, air flow is key for all of this to work. A good portion of the air flow comes from a cooling fan, usually located behind the condenser.
  • The condenser is the thing that condenses the high pressure, high temperature vapor into liquid. The cooling fan keeps it—you guessed it—cool.
  • Then, the Freon moves through a receiver/dryer, where moisture and contaminants are removed.
  • Then, it moves through an orifice tube or expansion valve, which controls the flow of Freon into the evaporator.
  • The evaporator turns the high pressure, high temperature liquid into low pressure, low temperature vapor.
  • Then, the Freon moves into the compressor, which compresses it back into a high pressure, high temperature vapor.


There are many issues that can arise with such a complex system, but here are a few that are the most common:

  • Foul odor from the vents
    • The air cabin filter (which keeps the air going into your vehicle clean) may be dirty and just need to be replaced.
    • There may be mold growing on the evaporator. Dirt can cause drains to clog. As a result, if any moisture builds up, bacteria, fungi, and micro-organisms will surely grow, if left alone.
  • No cool air
    • Freon may be leaking. Rubber hoses and connections are easily punctured and can expand over the years. There may be a leak at the service ports, in the condenser, or in the evaporator. Leaks can open up the system to a lot of other issues, so it’s important to fix them rather than just recharge the Freon.
    • The compressor or the clutch that tells it when to turn on may have failed. That means there’s nowhere for the low pressure, low temperature Freon to go; the cycle is interrupted.
    • The cooling fan may have failed, which can cause the system to overheat.
    • There may be faulty wiring or an electrical issue with components such as a temperature sensor, relays, fuses, etc.
  • Weak airflow
    • It could be something as simple to fix as a loose hose.
    • Again, the cooling fan may be malfunctioning.
    • There may be a restriction due to a dirty cabin air filter.

This is a 100% accurate representation of the feelings evoked when the air conditioner is broken.

This is a 100% accurate representation of the feelings evoked when the air conditioner is broken.


Because of the complicated nature of air conditioning systems, it is advised that you DO NOT ATTEMPT YOUR OWN REPAIRS unless you are a certified mechanic. The best thing you can do is to take it to your friendly, local Chad Miller Auto Care (or another honest mechanic shop if you’re not in San Antonio) as soon as you notice an issue with the air conditioning. Two things you can do to help prevent problems are to take your vehicle in for a tune-up at least once per year, and replace the cabin air filter at least once per year.


With the triple-digit heat upon us, now is definitely the time to be more aware of our air conditioners and how they work. I hope my buddy, Freon, and I helped you understand air conditioners better.


Have a story about a time that YOUR air conditioner broke? Leave a comment below!


Written by Ben Scharff

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