How to diagnose air conditioning that doesn’t work?

Driving in hot weather in a car without air conditioning can be uncomfortable and even dangerous in extreme heat. Diagnosing why your air conditioning is not working will help you determine if you can fix the problem yourself or need to have it fixed. You will also be less likely to be ripped off if you already know why it doesn’t work.

Turn on the air conditioning once you are driving
It will not work well if you are not riding. The best position for a diagnosis is the one that gives fresh air (not the one that circulates the air) with the air that comes out of the central vents when the air conditioning is on.

  • Start by putting the fan on full power.
  • If your car has a “Max AC” option, select it.

Listen carefully

This is to detect unusual noises coming from the air conditioning. Noise may indicate that there is a problem with your compressor and that it needs to be repaired or replaced.

Feel the air coming out of the vents

You will need to know if the air is cold, ambient or warmer than the air around it. Also note if it comes out cold, but then warms up or if it is generally warm, but blows cold from time to time.

Check all air outlets

Make sure that the air is well expelled from the air outlets that you have selected. Move the deflectors to see if the air is coming out of the right outlets.

  • If changing an air outlet does not change the airflow, you probably have a problem with the outlet deflector. You will need to replace the deflectors in the air outlets which determine the direction of the air.
  • On some cars, the deflectors close or open when you change the temperature to let more or less air out.
  • Sometimes an air conditioning system that encounters a deflector problem may work normally, but the air is directed elsewhere, for example, to the engine instead of inside the car.