No Condensed Water Coming Out From the Unit

Question

I used my Toyotomi TID-2400 last night for about 7 hours and when I woke Upthis morning to remove the drain tank I noticed that the drain tank is empty.I look around and but I can't find any water spilled around the place where I put the unit.Also I noticed last night, that the unit will switch sometimes to fan only. Is it natural for the unit to switch from fan to cool. I just noticed it last night. Ihave the unit since 2002 but I seldom use it.Your help regarding this matter is greatly appreciated.Thanks a lot.