When Car AC repairs are required one of the worst-case scenarios is having to replace the AC compressor due to an internal failure. When I say internal failure I’m talking about the compressor coming apart inside and spreading metal throughout the air-conditioning system.
Often both professional and driveway mechanics will just try to replace the compressor by bolting on a new part. This is an invitation to further repair and ongoing problems with the air-conditioning system. The small metal pieces that are hiding throughout the lines and other components will circulate and continue to cause problems.
Proper compressor diagnosis
In most cases when a compressor suffers internal damage the telltale sign would be the noise generated from the compressor itself while the clutch is engaged. You do want to take some time and verify that the noise is actually coming from the AC compressor and not another belt driven accessory.
Before condemning the compressor to be the faulty component it is a good idea to confirm this by fully charging the system and take some pressure readings. When a compressor has internal damage it is unable to pressurize the system properly.
Normal pressure readings on a summer day would be about 35 PSI on the low side. And about 150 to 200 PSI on the high side. These pressure differentials are created by the compressor itself. If the low side pressure is high and the high side pressure is low with a full charge this is a sign of a defective compressor.
AC compressor replacement procedures
The problem with replacing a bad compressor that is damaged internally is removing all a little metal particles from the system. Often both driveway and professional mechanics would like to just blow compressed air through the lines in the hopes that all of the pieces will be dislodged and removed.
The reason this doesn’t work is because the system contains an oil charge. This oil sticks to the inside surface of all of the lines and tubes. The metal particles then stick to this oily film. This is why the proper procedure is to use a liquid flushing agent to flush the AC system.
The AC flush chemical has similar properties to brake clean. When the liquid is forced through the system the oil is washed out and the alcohol base of the AC flush will dry the interior surfaces of the lines. With no more sticky oil film holding the little metal particles they are easily removed.
One of the components that cannot be completely cleaned with the AC flush procedure is the receiver drier. This component should be replaced along with the orifice tube when you are replacing the AC compressor itself. Flushing the AC system will not remove metal particles from the orifice tube or the receiver drier.
If someone replaces your AC compressor for you make sure that you’re getting your money’s worth and that they are performing the proper procedure. Ask them about how they will flush the system and how long they will guarantee the replacement of the compressor. This will often force them to take the extra step and do the job properly.
Feel free to visit my you fix cars website for a detailed list of the steps that should be followed when replacing car ac compressor. If you want to see just how bad professional shops are at diagnosing AC problems I have a hidden camera video on this page next page about trying to get car ac recharged. Or you can return to the auto repair information blog homepage for more of the latest posts to this blog.