How to Diagnose Your Car’s AC Issues? – Cerebrum Sensor

How to Diagnose Your Car’s AC Issues?

It can be difficult to miss the symptoms of a broken air conditioner. Especially in the midst of the summer and winter season, it gets uncomfortable without the proper functioning air conditioning and heating system. In most cases, a car owner would go to a professional mechanic to diagnose what’s wrong with the AC; this can be costly. Perhaps you might be able to diagnose the issues by yourself to narrow down the root cause. Let’s talk about how to run the AC diagnostic and save some cash. 

Some of the unavoidable symptoms of a faulty air conditioning system are:


AC is blowing warm air

So your AC is set to the coolest level but it is only blowing moderately cool air or not cool at all. You could be dealing with leaking refrigerant, faulty condenser or compressor, restricted flow of air over the condenser, or a damaged cooling fan. 


Foul Smell

You turned on the air vents and experienced a foul smell. This means your AC filter needs replacement. It is easy for mold and mildew to build up on the filters which create this foul smell. It is essential to keep the filter clean to avoid allergies from contaminants stuck in the filter. 



Leaks are the most common problem associated with the AC system. 

Check for the following to make sure they are secure:

  • Hose manifolds on the compressor
  • Crimped hoses onto the fitting
  • Pin holes in the condenser
  • Front seal and O-rings sealing the pressure switches onto the compressor

Still not sure? Check these components:

AC Compressor 

When diagnosing the AC components, It is a good idea to start with the compressor. Pop up the hood and look for the compressor. It is the only belt-driven component with a clutch. If you see a pulley that is not spinning but the belt around it is moving, that’s the compressor. The center part of the pulley does not turn unless the clutch is engaged. 

If the clutch is engaging and disengaging once every few seconds then this is a sign of low refrigerant. If the compressor doesn’t turn at all then there is something wrong with the compressor. Now that you know what the issue is, the next step is to check the pressure. It is advised to get the pressure check using special tools by a mechanic. 

AC Condenser

The AC condenser looks similar to a radiator. Air flowing through the condenser helps to cool down the hot gaseous refrigerant. The cooled refrigerant in the liquid state goes to the evaporator and absorbs more heat from the hot cabin air. This whole system needs to be air-tight. A tiny hole would leak the refrigerant or contaminants from the compressor could block the flow of refrigerant. It is easy to detect visible holes or clear damage in the condenser. One way to detect small leaks is by spraying water and heavy soap mixture on the condenser and fittings. 


AC Accumulator / Drier

Depending on the model, a vehicle might have an AC accumulator or a drier. Its job is to absorb moisture from the AC system. Physical damage might lead to desiccant material entering the AC system. A refrigerant leak can cause over-saturation of the desiccant material, which would damage the compressor. The accumulator is a cylindrical-shaped component located between the condenser and evaporator. A faulty accumulator could be identified if there is a rattling sound during operation, noticeable refrigerant leak, or moldy smell when the AC is ON. 


AC Evaporator Core

AC evaporator - as discussed earlier - cools down the hot cabin air with the help of refrigerant. A common cause of evaporator failure is wear and age. Some of the symptoms of a faulty evaporator are uneven cooling and a strange odor in the air coming out of the vent. A strange odor is typically due to the leak of refrigerant into the air coils of the evaporator.

Now that you’ve equipped yourself with a basic understanding of the functionality and common failures of the AC system, you can determine if a repair is within your ability or better suited for a professional.  Either way, it’s time to get that AC system repaired!

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