Go down to the end of the pipe (near the fan), turn left and crawl into the duct. You'll see a grating. Listen to the bad guys talking below. Throw your lightsaber to break the grating. Toss down a det pack or TD and blow them up. Drop down and you're on your way.
P.S. - don't waste time trying to kill a large animal you will encounter there because a new one will spawn to take its place. Just distract and avoid it.