Upon arrival performed an operational inspection of the heat pump and noticed frost forming on the condenser coil seconds after start up. The heat pump continued to short cycle even after the new EEV head was replaced on the valve. The unit also showed 3 different alert codes at the heat pump. Suction pressure temp sensor is out of range, compressor is not pumping and low superheat cooling mode. The EEV head is not the issue at this time and must return with replacement sensors under the recommendation of Trane tech support.