The wooshing sound you are hearing is the reversing valve shifting. This typically happens when the unit goes into a defrost cycle. If the unit is going into defrost cycles every 2-5 minutes it may have a bad defrost terminator causing it to send false signals to the defrost board. I would definately have it checked out, you don't want to knock the compressor out of it. But if I were a betting man, I would lay my money on the terminator.
CARRIERMAN, I ran across this at my facility just a couple weeks ago. I kept getting a heat pump kicking out on the high pressure switch. I couldn't figure out what was going on and I didn't have time to baby sit it and it continued for another couple days. I finally was able to check it out and when I was in front of the unit, heat came on, and then about 5 mintes later the 4 way switched, then it switched back and did it back and forth until it tripped again. Turned out the T-stat was failing.
So, Silhanek, it could be that the defrost is trying to come on or you have something de-energizing (or energizing) your 4 way valve. Best thing to do is call someone to look at it. There are a few things it could be and getting a tech to look at it would be the cheapest in the long run.