Disney’s 2013 animated “Frozen,” inspired by Hans Christian Andersen’s “The Snow Queen,” wasn’t just a hit. It was a cultural tidal wave, a ubiquitous phenomenon thanks to Robert Lopez and Kristen Anderson-Lopez’s soaring songs, particularly the inescapable, Oscar-winning “Let It Go,” belted by Broadway powerhouse Idina Menzel. Six years later, the Elsa Halloween costumes have yet to grow cold. So when it comes to a sequel, the only mandate is: “Don’t muck it up.”

The good news is they haven’t. The bad news? That’s about it. “Frozen II” doesn’t represent some giant leap forward for the “Frozen” universe, it merely keeps the franchise on track. For many, that’ll be fine: more adventures of Elsa (Menzel), Anna (Kristen Bell), Olaf (Josh Gad) and Kristoff (Jonathan Groff). But the movie has all the staying power of a snowflake: It evaporates almost on contact.

Once again helmed by Jennifer Lee and Chris Buck, “Frozen II” merely drifts pleasantly in and out of our consciousness, a diverting way to spend an hour and 43 minutes with some great tunes and lovely snowy landscapes to ogle (just wait until kids get a load of Elsa’s new ice horse). It will of course be seared into the brains of parents and kids after their millionth viewing. And it’s enjoyable and funny enough to be tolerated that many times, which seems to be what it’s designed for.

What made “Frozen” rather revolutionary was its sisterhood story that resonated with so many people who were sick of seeing the same old princess-saved-by-a-prince tale. A princess saved by a princess? Now there’s an idea. The snowy story about sisters powered by power ballads is infectious, and Disney hasn’t messed too much with the formula.

Elsa is now queen of Arendelle, playing charades with her sister, Kristoff and Olaf, enjoying a bit of domestic bliss. Like almost every animated hero, Disney and otherwise, there’s a bit of singing about how great things are where they are right now, which is of course, foiled by an existential threat. Elsa’s plagued by a mysterious voice from the forest, coupled with some inclement weather. Recalling a folk song her mother (Evan Rachel Wood) used to sing about memories in an ancient river, she decides to dive into her ancestral history to discover the source of the voice, save Arendelle and free the forest from a persistent fog. She does so, of course, with her sister, her sister’s boyfriend, their snowman and a reindeer in tow. Isolationist Elsa insists she has to make the journey alone, but like all the emotionally healthy, therapized Disney heroines of late, she learns she can’t do it all alone and accepts Anna’s help.

The songs by Kristen Anderson-Lopez and Robert Lopez are bangers, naturally, and parents might be glad to discover that the catchiest song on the soundtrack isn’t an Elsa belter, but a pitch-perfect ’80s power ballad sung by Kristoff (ready those karaoke pipes). If only the rest of the film were more memorable. It’s not a disappointment by any means. It’s what you expect from the characters and world, and it gets the job done. But the most enthusiasm one can muster for “Frozen II” is it’s perfectly adequate, unlikely to create a seismic cultural shift like its predecessor.