Sounds like too much heat / moisture is getting in. Could be environment, frequency and length of time door remains open or a door seal gap. Mine seals extremely well (if you listen closely after closing door, you should hear a slight fan / vacuum noise for 5-10 seconds, then stop). Door may be a little more difficult to open than what you may be used to, this indicates the seal is likely OK. I wipe mine down every month or so to make sure it seals tight. If it's in laundry room, possibly excess heat in the environment & getting it when door is open could cause your issue, especially where it is collecting (highest point inside).