I'm hearing something cycling on and off while in park with the engine running. It's doing this with the fan on or off and with the AC on or off. Whatever it is will kick on for about 30 seconds and then kick off for about 15 seconds. It's driving me crazy because it's noticeably louder when it comes on and I can feel a vibration as well. I tried listening outside of the car with the hood up but the engine noise drowns it out. It's just really obvious when sitting in the car. I never noticed it doing this until a few weeks ago, but maybe it has been all along. Just wondering if anyone knows what it could be. Thanks.