Heat check completed on one horizontal heat pump system. Drain line was cleaned and treated. Condensing coils were cleaned. All mechanical and electrical components were checked. I did find a faulty thermostat, the fan circuit was stuck in the closed position enabling the fan to run constantly. Presented options for replacement of the thermostat and he chose to replace the thermostat today. Once the thermostat was replaced, the system was cycled in all modes to verify proper programming. No other major issues were found. The system is heating properly at time of departure.