Saturday, October 15, 2011

What causes INTERMITTENT COOLING on Car AC system?

There are two types of AC systems.
1) Manual AC system. And
2) Automatic AC system.

In both AC systems this intermittent cooling problem is noticed.

There in not one possibility for this problem.There are many possibilities, and that all needs to be checked and inspected.
The possibilities on Manual AC system:---
The problem with low pressure switch.

This switch stops compressor from running if the refrigerant level is low. In this case first the refrigerant level needs to be confirmed.If refrigerant is up to the required level then problem is the cutout switch.

The problem with AC controlling switch.The switch which you use to control the AC.This switch gets loose or shorted internally and can cause such intermittent cooling problem.The switch needs to be visually inspected, but if it looks ok, then has to be tested by removing it from the control panel.

The problem with compressor clutch:-- The compressor clutch is the part,which first engages then it makes the compressor run.But if clutch is faulty then it will not engage and compressor will not run.In some cases the compressor clutch coils gets burned,so they get weak and you notice intermittent cooling, because clutch is not engaged properly.So compressor runs and shuts off.Testing the clutch voltage and resistance by volt meter and test light should help.

The problem with compressor clutch relay:--- The compressor clutch gets power from clutch relay.If the relay is faulty, then clutch will not function.So before replacing clutch,inspect the clutch relay.You can try this test.Bypass the relay with a fused jumper wire and connect clutch direct to the battery and then see if the compressor runs.If yes then relay is faulty.If not then clutch is the problem.

This are most common possibilities on Manual AC system,which goes faulty and causes this intermittent cooling problem.


The possibilities on Automatic AC system:---
On automatic AC system.The problem is causes by faulty AC control module .Also known as HVAC module.Or the other possibility is problem with sensor.

There is a scan test done at dealer or at professional auto parts store.On automatic AC systems, the problem has to be detected by scan test.Your AC system is scanned by the tool and in that you receive error codes.As per error codes.It points out towards faulty part.So as per that you have get the parts repaired or replaced.
There are sensors like,temperature sensor,Ambient sensors ,interior air temperature sensor, evaporator temperature sensor, or sun-load detect sensor. Testing all this sensor and module manually is not a easy task.But getting the module scanned bu the scan tool makes the task easy.It points out towards the problem.So you can look into that area.

All the above possibilities mentioned are electrical possibilities that cause intermittent or no cooling problem on car AC.
But there are many other possibilities related to refrigerant and other components related.
Click this link below to know about more possibilities for this problem.


For more car related AC problems.Click the link below:---
Car AC Blows Warm Air ?

How to test AUTO AC pressure?

AUTO Air Conditioning Troubleshooting?


Fixing refrigerant leak?

How to locate Car AC Refrigerant leak?

For more car problems help.
This are best blog sites to refer:---