1989 w124 300E
The doors will not unlock when attempting from the trunk lock, and the locks will not budge when I try the key in both doors.
So, central locking is down....Do I need to break in and change out a part? (I am in the Southern US, so nothing is frozen).
Thank you!

FYI
I am carrying in my coat, a small impact case with vial of alcohol and 10cc syringe with needle, due to door lock tumbler icing. This option is much cheaper for me, than the small spray lock deicer.
At the local CVS pharmacy a 10cc syringe with needle is $0.28 each, and a quart of CVS brand rubbing alcohol is $3.00......

A full 10cc shot of rubbing alcohol takes roughly one minute to deice the tumbler.

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Thanks. I guess I should have mentioned I live in the south where there have been no freezing temps yet.

It definitely sounds like the vacuum system is down, so you need to start at the vacuum pump and then check hoses and actuators.
I'm going off of memory, but I thought the key works on the lock you're opening even without vacuum. If not, then yes, I think you need a locksmith or Bilbo Baggins.

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