The little threaded rod/knurled knob doo-hicky from the factory does work for keeping the fridge door closed while traveling. But it's easy to lose and sort of a pain to install/remove.
Here is a cheap, easy (and very dorky) alternate
I went to Home Depot and got 2 pieces of foam pipe insulation. One is for 3/8" copper and the next is larger for 1 1/8" pipe. They sell the soft rubbery foam and the stiffer type foam. Get the stiffer type. On the larger piece, get the type that you peel off the plastic and the sides have contact glue on them. Each piece is like 8' long and costs $1.68 each.
Use whatever length suits you but I cut a 3' chunk from both pieces. Take the smaller diameter piece and roll it up tightly so it fits inside the larger piece. Pull off the tape and stick the sides of the larger piece together.
You can now stuff this between the edge of the fridge/freezer door and the woodwork in about 2 seconds and remove it just as easy. It really wedges the door shut pretty good.
My wife, of course, is the creative one who just had to sew a cloth covering for it and add a head so she could call it the "Fridge Snake". The "Snake" fits perfect above the wood trim when not in use.
For your $3.76 you get enough to make 3 so you can have spares, give them away for Xmas presents (just kidding)