Hi I just got a 2002 elantra the other day and there's a rattling noise present when the car is started but goes away after a while. I had someone check it out and they said that it's the AC because it hasn't been ran all winter. Well when the AC is turned on, it goes away. I'm assuming there's some kind of rust around it. It doesn't affect the way the car drives, it just makes a really annoying noise. I'd just drive around with AC on but when it's 20 degrees outside, it's not an option lol. Any ideas? Thanks.

 

Do you use defrost in the winter at all? If you do, then the compressor runs. The AC compressor will run on ANY defrost setting even if you have the heat selected. That's to keep the seals from drying up and cracking in the cold weather if the compressor didn't run at all. It won't blow cold air until you turn the AC 'on'. A bit of rust shouldn't cause a noise. When was the last tune up performed (ie. spark plugs, timing check, compression check etc)?