where does the call for the reversing valve come from during defrost? I have a lennox HP that is putting out 4~5 volts during a call for HEAT. It wont go into defrost when forced from the defrost pins (defrost stat jumpered closed) but will defrost if i jumper R-O on the defrost board and pull the fan lead. This tells me the board is bad but wondering why I'm getting the voltage on the reversing valve wire. Any thoughts?