Arrived for no heating on heat pump system in attic. Heat pump was locked out on high pressure switch being tripped. Checked electrical components, refrigerant levels and coil on heat pump. Heat pump coil is dirty and highly recommend a proper coil cleaning. In attic air handler is zoned with 2 14" dampers for upstairs and downstairs. Bypass damper was set low at 2" w/c and was open. Checked all electrical components, filter (18x25x1), heat strips and drain line. Found system pressures were raising high from lack of air flow across air handler coil. The zone board is sending 18v to dampers and zone dampers are not opening fully. The downstairs damper is stuck in its current position. Spoke with homeowner and presented repairs options as well as recommendations to system.