[folivier]

Tom is right about the amps drawing on each unit. I think Newell charges the freon based on the amp draw rather than pressures. The only experience I had was a bad compressor and it would trip the breaker. Replaced compressor and it is good.
After you determine the amp draw, check and see with unit running is the compressor/evaporator fan running?
Sorry, but that's the extent of my knowledge. Have you found a local a/c guy to check it out? These are more like a house a/c unit rather than a rooftop rv type. When in Salt Lake I convinced a local guy to come out and check out my unit (after calling 5 others). He pulled it out, checked and determined the compressor was shorted and would need to be replaced. Unfortunately his price was much higher than Newell's so I stopped at the factory for the work.