CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Cold Air - it isn't!

My 2002 Altima A/C won’t blow cold air. Took it to my mechanic who says all switches, fuses, relays, compressor clutch are OK and system has pressure, but the compressor is shot. In order to get a replacement that’s guaranteed I have to get a receiver/dryer with it. Also says not to get a compressor from the salvage yard. I’m wondering if there are any other testing procedures that could be used to be certain it is the compressor

A set of manifold gauges will tell the story, which is probably how your mechanic came to this diagnosis. If you question his diagnosis, you could take it to another a/c shop to diagnose it. Just don’t say anything to him other than that the a/c doesn’t work and you want to know why. See if opinion number two matches opinion number one. The reason a used compressor is not recommended is because they can be hit or miss and could even introduce contaminants into your system, depending on the part’s history, which could damage your a/c system or your mechanic’s a/c service machine (they are not cheap, usually start around two or three thousand dollars for a cheap one). It is also true that you must replace the receiver dryer with the new compressor to avoid contaminating it and damaging it. A new orifice tube or expansion valve, depending on the design of your system, is also a good idea to ensure the best performance and longevity of your system I think your system uses an orifice tube, and they are only a few dollars…

What needs to be known is whether or not the compressor is actually engaging (assumed it is based on the clutch is good comment, but…) and what the system pressures are on both high and low sides and even the static pressure. Without knowing that it’s impossible to know if you need a compressor or not.

If in fact the compressor clutch is engaging and the system pressures are not changing, that means the compressor has failed. If this has happened, you will need to replace it, along with the receiver/drier. If the compressor failed in such a manner that internal pieces broke, you may need to flush the entire system as well.

New complete compressors are often available at almost the same price as rebuilt units. Why would you buy a used compressor froma salvage yard? You already have a used on on your car.

Thanks to all for the input/advice.