With it in auto....no fan and no compressor (but fan does work)
Could be as simple as start/run capacitors, thermostat or bad compressor motor
Units can be 'serviced' as in fan motor, capacitors, replace thermostat etc BUT w/o adding service valves units are sealed on coolant side.
If not handy, understand DC & AC electricity and know how to use a voltmeter it would be best to have mobile rv repair check unit out......
If handy these should help
Installation manual for 579 seriesDuo-Therm Service Manual...pg. 104 troubleshooting for roof top A/C Units
