NSW man freed from university's air-conditioner duct after six hour ordeal

A man has been freed after being stuck in a university air-conditioning duct for more than six hours in regional NSW.

Police say the 23-year-old had spent Saturday night at a Bathurst pub before climbing onto the roof of a building at Charles Sturt University, at about 2am on Sunday, and then entered the vent.

The man, who is not a student at the university, was heard yelling by patrolling security guard and was rescued by emergency services just after 8.30am.

"The rescue squad actually had quite a bit of difficulty," a police spokesman told AAP.

Duty Officer Andrew Spliet told Fairfax Media he was amazed that the man was able to climb the steep roof gradient.

"They (rescue squads) had to rope themselves up the wall and once up there, they had to unbolt the air conditioner.

The man was given water before he was pulled out and checked by paramedics.

He was uninjured but faces trespassing charges, police said.