Per @TabloTV, the safe operating temperature for Tablo is 41°F to 95°F (5°C to 35°C) so it sounds like your garage may be pushing safe boundaries.
I have my Tablos installed near my primary TV and found that even there, with a room temperature of 68 to 72 degrees, it tended to overheat at times. I added a laptop cooling pad under the Tablos and hard drives and haven’t had any overheating problems since.