I got called to a small(ish) store yesterday. They have two highcool (from Climate Center) wall units. One at the front of the shop 12000 btu (3.5kW) and a 18000 (5kW) at the rear of the store. Apparently the rear unit ices up when he turns it on in the morning, so he had to turn off and let the ice melt off. I noticed the heat load in there is quite high in the middle,but OK else where. Put some gauges on (R407C) and read evaporating temp of 4 degrees C and discharge was also within limits. Gas charge is OK and pipe run is only about 6 metres, so have eliminated all this. Filters are clean, and the airflow seems OK. I was there during the day when the ambient temperature was about 14 degrees C or so. These units have a very primitive fan on and off control to keep head pressure at about 200-235 psi or so. The customer has said that he isn't running the units at night, but I think that might be a little white lie. The only assumption I have made is that a fan speed controller might do the trick, as he is using it to cool whatever the outdoor temperature, because of the integral dairy cabinets inside. The thing is that this does not seem normal, and only the larger unit seems to have this problem. HELP!!