It sounds like you have lost a start capacitor or possibly the compressor. The blower will start for just a bit before the compressor kicks in. If the compressor fails to start the system will time out and shut down. The sequence will continue to repeat itself until shut off at the thermostat or obviously the power is unhooked. Sounds like a trip to someone who knows RV air conditioners is in order. Just a tip from a bad experience, make sure they know RV units as they are somewhat different than home or automotive.
2016 Sandpiper 380BH5
2011 Ram 2500 4X4 MC Cummins