Removed old equipment and installed new Rheem 3 ton heat pump and air handler. Installed new return plenum with 16x20x1 filter, new emergency drain pan, new pan safety switch, new coil safety switch, new thermostat and new composite pad for outdoor unit. Reconnected high voltage, low voltage, drain line, supply plenum, and all return ducts. Tested system operations, set proper refrigerant charge. Talked with Keith on adding refrigerant to old upstairs unit. While trying to turn the unit on the compressor would not start on old upstairs unit. Per Keith he said to send a tech out on a courtesy call to see what the issue may be.