I have my Fridge set to -18C / 4C and this morning when I woke up, it was actually at -25C / 13C. However, the set points never changed. I took the air filter housing off to inspect the damper door to see if it was blocked and I noticed frost on the air filter housing vents. I also noticed that the damper was wide-open. I decided to put everything back together and see if the problem corrects itself, and, it did. The fridge is now at -18C / 4C and working properly. Do you think the Fridge was just defrosting itself? Or, is there an issue. (FYI, it is 2 yrs old and has worked perfectly up until now). Thanks the help.

Air Purifiers - Frigidaire