I didn't realize that the juice containers on these actually mixed concentrate at a customer-selected 'richness control'. This looks to be in great cosmetic shape, but like so many, it runs but does not get cold.
There was a slant-handle Westinghouse in the 50s that had a similar juice fountain feature, but it, of course, was all inside the refrigerator compartment. It was about 1954 or 55.
I have seen the Westinghouses, but didn't realize that they also blended from concentrate. But having to open the door isn't nearly so handy as this Frigidaire. You are quite right about the year, see the attached 1955 advertisement.
I remember when growing up that we "made" orange juice... from the frozen cans of orange juice concentrate!