I have a question about the a/c on our 1997 Mercury Tracer. When we started using the a/c this year, we noticed that the air wasn't as cold as it normally is. We also noticed that the idle of our car would flip back and forth when we would have the a/c on and were stopped at a traffic light. So, we took our Tracer in and were told that it needed freon and the compressor would need to be replaced relatively soon. They added freon and the a/c works great. Also, the idle flip doesn't happen anymore, but there have been issues lately with a weak idle when the a/c is not on. Here is my question. Would an air compressor/clutch affect the idle or performance of an engine if the a/c is not on and the compressor has not locked? I'm asking this because it would cost us approximately $700.00 to replace the compressor and I'm worried about getting our car back from the shop and having a more urgent problem. Any information would be greatly appreciated.
-Joseph