Heating tune-up completed on a vertical heat pump. Drain line was flushed and treated. Condenser coils were cleaned. All electrical and mechanical components were checked. I found the outdoor torque booster below minimum charge recommended by the manufacturer. The homeowner chose to replace the outdoor torque booster today. Once repairs were made, the system was cycled on to verify proper operation. No other major issues were found. The system was running at completion of service.