Will this freezer operate well in a garage that probably averages 75 degrees F during the year, but could range from 20 F - 105 F at times? Any suggestions for operation under these conditions?
Your freezer will work fine in your garage. Many people put their old refridgerator in the garage and it works fine. most people I know put their freezer in their garage due to lack of space elsewhere. I was a major appliance repair man 20 years ago and never had a call that was from the unit being in the garage. In fact, I have had my freezer in my garage for ever and never had a problem (In south Mississippi where it gets very hot and humid) and my old fridge is there also, with no problems. Dont worry, it will operate fine.
I have an old freezer in my garage with termperatures range from 20F - 110F or so. The winter time the freezer doesn't run too much, but it does seem to run almost all summer. On a side note if you have a GFI in the garage you might want to keep an eye on the freezer, or get a temperature alarm incase the GFI trips, your food might spoil. I had a dedicated circuit put in and have had no problems.