Troubleshooting An Air Conditioner That Only Blows Warm Air

8 June 2016
 Categories: , Blog


Nothing could be worse than a car whose air conditioner suddenly conks out--especially if it happens right in the middle of summer. Luckily, diagnosing the cause of the problem may not be as difficult as you think. If you have a basic knowledge of automotive parts and skills, and would like to learn more about the inner workings of your car's AC, read on. This article will teach you how to troubleshoot an air conditioner that only blows warm air.  

The Compressor

You're going to want to start by checking to see that the compressor engages properly when the AC is on. The compressor, which is easily locatable beneath the hood of your car, is driven by means of a special belt. With the hood open, start the car and turn on the air conditioner, then go check whether the compressor is actively running--i.e. whether the drive belt is providing momentum.

If not, your next step should be to assess whether the compressor will run when connected directly to your battery with a fused jumper wire. If you can successfully jump the compressor, and if the air conditioner indeed begins blowing cold air, you will know two important things:

  1. The system does contain refrigerant.
  2. The problem has to do with either the compressor's clutch relay or a bad internal switch.

If not are not able to jump the compressor, you are most likely dealing with a faulty compressor clutch. If on the other hand the compressor can be jumped successfully but the does not produce cold air, the issue is probably that your refrigerant level is too low.

The Refrigerant

Refrigerant is the life-blood of your car's air conditioning system. When there is too little refrigerant, or when the refrigerant is not under sufficient pressure to circulate through the system, an AC will cease to produce cold air. Begin by using a pressure gauge to determine the pressure level of your refrigerant. 

In order to get a useful reading, you will want to connect your pressure gauge to a service port on the high-pressure side of the system. This port is generally found on the hose running between the condenser and the compressor. Air conditioning systems generally contain a so-called low-pressure cut-off switch. This keeps the compressor from working when the pressure drops below a level of around 45psi.

If your pressure seems adequate, then you may be dealing with low refrigerant levels. This can be easily remedied by recharging your air conditioning system. Contact a local outlet for additional info.