The Chilling
(1989)

Dr.Miller (Troy Donahue) runs a cryogenic facility that freezes people who just died, to hopefully bring them back in the future.  It is a scam, but he figures no one will ever come back to revive the bodies.  Mary (Linda Blair, of exorcist fame), his naive marketing director, is shocked to discover his deceit.  Joseph Davenport is an annoyingly sincere rich guy, whose wife and son are frozen there.

A storm takes out the electricity, thawing the bodies.  Lightning hits the metal chambers, bringing the dead back as flesh eating zombies.  Miller's slimy assistant somehow knows that the only way to kill the zombies is to freeze them again.  Zombies kill the assistant, Mary's boyfriend, the cowardly security guard and a few others.  The zombies put Miller in a cryogenic tank, freezing him alive.  Mary, Joseph and the bearded security guard use liquid nitrogen to defeat the zombies.

Title cards at the end tell us that Mary and Joseph got married.  Joseph bought the cryogenic place and converted it into a public park.  Dr Miller is still frozen.  

Thanks Joseph C!