rheem and economisers

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 .

what is the minimum pot set at......

Set at minimum position , i am new to rtu,s always worked on refrigeration and ductless systems , my understanding of the economiser , is that if the outdoor air conditions are good as checked by the enthalpy and temp sensor , when the system is in A/C, the damper will open and let outside air in for ;free cooling;, why is it operating in heating mode [heat pump] , thanks jim