Hissing noise coming from frontpassenger side?

[captkservices]

I bought a 2011 F-250 on Saturday. It now has 800 miles on it and I noticed a hissing sound coming from the front passenger side? It comes and goes every 15 seconds or so. Sounds like air is slowly being released, lasts about 3 to 4 seconds at a time.It will make the hiss for a couple seconds, then go away. Then do it again 15 seconds later. Doesn't seem to matter what speed you go, whether you are accelerating, braking, or coasting?

Has anyone had this happen?

[GRFord]

Check your air vents. Mine make that noise if one is closed all the way and air is trying to blow out.

[LFD132]

Originally Posted by captkservices

I bought a 2011 F-250 on Saturday. It now has 800 miles on it and I noticed a hissing sound coming from the front passenger side? It comes and goes every 15 seconds or so. Sounds like air is slowly being released, lasts about 3 to 4 seconds at a time.It will make the hiss for a couple seconds, then go away. Then do it again 15 seconds later. Doesn't seem to matter what speed you go, whether you are accelerating, braking, or coasting?

Has anyone had this happen?

Mine does the exact same thing. I was thinking it had something to do with the climate control system.

[mor4wd]

It's the cabin pressure being released out of the one way vents. Turn off your fan and it will stop. The pressure in the cabin builds up until it can push the flap open on the vent in the rear and it releases then closes and does it over again.

[AlbertaStroker]

I've got almost the same sound coming from the passenger side up front under the dash. Mines almost like a fan spinning then dying. Then coming back and dying again. Does it in like 2-3 min intervals