Let’s just hope this isn’t Metro-North’s new open-door policy.

A packed commuter train, a door stuck wide open, hurtles at full speed toward Grand Central Monday, sparking emergency inspections by the MTA.

No one was injured in the freak 3-minute incident aboard the 8 a.m. train out of New Canaan, a video of which was posted on YouTube yesterday.

Frigid temps had frozen the circuit that controls the door at the 125th Street station.