At work the mobile modular office that is the sales office for the new construction homes, the heat pump wasn't cooling down the office. Since they couldn't bare the heat till tomorrow they had a service technician from our company take a look at the system.

I know this guy so I was talking to him while he was checking the unit. On two of the three units he found a sheet of ice, I would say 1/4" thick at least. He pulled it off and through it down. He checked the superheat and the low pressure was at 96. High pressure at 300.

He said that the system was overcharged. He said that they had the thermostat at 68 degrees and at night it remains at 72. He said while the low side pressure was at 96 degrees at night when it cools down the pressure in the low side drops much lower. He said the moisture in the air runs across the cold evaporator coil and begins icing over, until it becomes a sheet of ice. The sheet of ice was restricting the air flow.

Is this right??

He explained Dry Bulb, and Wet Bulb. So before I take what he said as fact.

Dry Bulb: Outdoor Tempature

Wet Bulb: He said that you take a the thermister and wrap it in a wet cloth and swing it in circles inside the R/A vent. He said this measures Humidity in the air.

Sounds weird as hell, please no sarcasm, I'm here to learn from you gentlemen.