Norcold 1210 turning it off for two days fixed it, why?

I have a Norcold 1210 refrigerator (new cooling unit April 2021). Old cooling unit died (ammonia smell) after ten years of full time use. Issue started a few weeks ago when the freezer could not freeze a tray of water for ice cubes. The freezer did have a build up of frost. While troubleshooting fridge it acts the same on LP & electric replaced thermistor and thermostat located on the fins at the top outside. At times the refrigerator fin temp (option 3 main display) would reach the low 30's then a few hours later it's back up to 44 degrees. After a few days I gave up and shut it down, two days later I turned the refrigerator back on LP and the fin temp went from 49 to 34 in a few hours, left it overnight in the AM temp was 19 degrees. Refrigerator has been running for two days the fin temp is staying between 19 and 24. I did hear the outside cooling fans running from time to time.