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I've been learning a great deal about a/c lately as I've just finished replacing the compressor and accumulator in my truck. While it's a different vehicle the concepts are pretty much the same.
If I were a betting man, I'd bet your low on freon. It may have been a slow leak that caused your problem in the first place.
It is entirely normal for the compressor to operate intermitantly. A normally functioning a/c system will cycle off in cooler temperatures to prevent the lines and evaporator core from freezing up. In a system that is especially low on freon, the system will cycle frequently -say 8 times or more a minute no matter how hot or cold the ambient temperature is. If your compressor won't turn on at all, it may be freon is so low that the pressure switch (normally attached to the accumulator) won't close -which shuts the compressor down. That's a good thing. It keeps your compressor from burning itself up and may be what your Indy is mistaking for a short in the system. You might find the switch on the accumulator, and jump the connector to see if the compressor clutch engages.
Also whenever the system is opened up, and components replaced, the service technician must vaccum pump the system to boil out moisture that enters whenever air gets into the system. Some shops don't bother to vacuum pump or use cheap pumps that are run off compressed air. These do not produce enough vacuum to allow the moisture to boil off at normal ambient temperatures. I bought a 2 stage pump that could pull close to 30 hg which reduces the boiling point of water to -35 deg F. a pump pulling 28.5 hg only boils moisture at 86 deg F. by comparison. Failure to do so can lead to poor cooling, internal corrosion and premature component failures. Excessive moisture in the system can also produce noise -perhaps the whining your hearing.
Your tech should also have replaced the receiver-drier (accumulator) which contains a dessicant and traps crud. If they didn't it would further increase the likelihood of excess moisture and perhaps restricted refrigerent flow in the system. And of course, if you have a leak in the system, you'll eventually get air, and the moisture it contains.
Take it to a shop that specializes in a/c and have them check for leaks. (there are a number of ways to do it). if there are no leaks, and the compressor works, they may just deep vaccum the system, recharge and send you on your way.
A Saab 9-5 fully charged takes 31 oz of R134a and 5 oz of PAG 100 oil (only use what you remove when replacing components). That's a little over 2 1/2 12 oz cans ($6-7/can) The PAG oil isn't that expensive and you probably won't need any.
posted by 66.227.1...
, Wed, 30 May 2007 13:46:07
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