Loud Noise

honda
odyssey

#1

Our 2006 Odyssey when idle makes a loud noise that sounds like pressure is being released from too much air building up somewhere. It does this about every 30-40 seconds. Just started three days ago after I turned the A/C on for the first time this year. Is it the air compressor? Relay switch? There is also a smell when all this is happening- Freon?