Arrived to No Cool on 2nd floor System #1 : Model #TWE06044AAA03A00 Serial #20102751BA System #2 :Model #TWE06044AAA03A00 Serial #20101344BA Identified faulty remote temperature sensor on System #2. Reading 0 ohms of resistance through sensor. Replaced remote temperature sensor with System #1s remote temperature sensor to confirm fault, System #2 detected temperature and functioned as designed. Once system #2 was operating, identified low pressure lockout, identified belt had come off the indoor blower sheaves. Belt is in horrible condition, photo attached. Recommend replacing A42 belt. Put belt back on to test system, checked system, identified extremely low refrigerant levels, (diagnostics photos attached), identified two leaks in system. first leak identified in evaporator coil, coil is severely rusted, second leak identified on lineset, leak is on backside of horizontal portion of 90 degree elbow (photo attached). Factory charge is 10.5 pounds of R-410 based on system pressure