So i picked up an old chest freezer on craigslist today, approx 15 cf. The compressor runs but i cannot get the temp to drop below 60 degrees (using digital probe therm, the freezer doesnt have a readout). It is approx 67 degrees ambient here. The inner walls are cooler than air temp by a bit ( i believe this is how it cools?). I dont see any air vents on the inside. Any thoughts? Might it just need freon? will this thing be worth the hassle? I already have to clean it up a lot, including a paint job.