MKirkland wrote:
What amperage do you end up with (110 House receptacle/20 amp adapter)?
Could this be the root of the trailer owner's AC problems? Some have said hard to know.
That is because it IS IMPOSSIBLE to know without knowing what ALL of the component parts ARE and how they are performing.
The remaining questions/factors have been well covered when you take all of the answers together:
There may be a high resistance in the adapter and the under-sized receptacle.
There may be a high resistance in the WIRE used for the circuit; I think the minimum for 30 amps is 10 gauge.
The connections at the receptacle or the box might not be tight enough.
A high resistance anywhere will limit the current capability.
The breaker itself might be worn out.
A professional with some standard equipment should be able to pinpoint the problem....or problems....in a relatively short time.