Upon arrival they were not sure which unit was down. I found unit 2 off on float switch. I vacuumed all three drainlines. While vacuuming lines on unit 3 I found it completely iced over. I shut condenser off and rescheduled to return tomorrow to check charge and leak check again. I am sure now there is a small leak in evaporater coil. I checked 6 months ago when had same problem and thought I repaired leak at that time. I could not get thawed out in time today before office closes.