A Rheem 5 ton heat pump rtu , a couple of months old . An economiser was added to the unit , controlled via enthalpy on the damper inlet and a temp sensor. The site maintenace guy has found the econmiser opens up to 45 deg , even on very cold days , allowing a lot of cold air in to the office below. all settings as per rheem , checked another installed at the same time and the same thing is happening , ?, can you give me some advice please .