03 - Wheel is hissing when parked.

[Jesda]

This is the Navigator's first time in cold weather (25-35F). Last night the suspension failed to raise and gave a suspension error message. It did the same today, but eventually started working on the way home.

After I parked, I heard a hissing noise coming from the front passenger side wheel. Is the air bag busted?

2003 Ultimate, 2WD, 57,000 miles.

Thanks