Hello, I have a 2000 S70 Turbo I had noticed that if my AC was on, t would make engine sputter at idle a bit and now when ever I start my car there is a sound in the beginning for a few seconds and then stops. A mechanic listened when I started the car and he said it the AC was cycling on. It happens even when AC isn't on. Any ideas what causes this? Is it something we can fix ourselves? I read on the forum about adjusting the clutch with a shim but it seems that's for when it doesn't cycle on or cool. When the AC is on, it blows cool air but it sounds like a cycling on and off every 1-2 seconds. Any ideas? Thank you. Also, any pictures you could direct me to would be appreciated. My husband and I refer to forums and youtube and have kept my car going really well for the most part to 236,000 so far with out being mechanics at all. Of course we have used an actual mechanic for more complicated things.Thanks so much!

 

You should be able to see the compressor engage from beneath the car (not sure how to suggest doing this safely...) but just the same, you can try pulling the fuse or the relay that controls the AC to see if that stops the cycling. In my experience, short cycling when the AC is on can be caused by low refrigerant levels (ie AC kicks on, low pressure sensor trips it off, system cycles and AC kicks on etc). Similarly it could be the clutch shim problem (lots of info on the 850 board on how to replace or reshim the clutch ). In my case, the AC would run fine for 10 minutes, then the clutch would overheat and stay off until it cooled rather than cycling. I'm not sure if the S70s have a vacuum pump - my 2000 S40 has one it it cycles on/off when it needs to... particularly when the car first starts up to build up brake booster pressure. You may want to check into that as well.

 

Thank you. It turned out to be the relay.So glad it was easy. Thanks so much for the help!