Wlelcome to the Fourms David.
Really the Reefer is one of the items that is the same as any other RV is going to have. Any reputable RV dealer with a Repair department should be able to help you. I would call for a quote and not even mention its in A Airstream. Just give them the brand and model of the Reefer.
I would go to the Manufacture's web site and they will probably have a list of authorized repair facilities. See what is close and then check around for the reputation of the facility.
1959 22' Caravanner
1988 R20 454 Suburban.