Roof a/c problem update

[RJay]

The could be three explanations:

The shore power has low voltage.
You have a bad start capacitor.
The breaker needs replacing because it has become weak from the constant tripping.

[Jbrie69]

Check the start Cap. See if you see oily resedue or it looks out of shape (bulged out)

[JimM68]

with fingers crossed, I'd replace the breaker first. Quick, easy, and cheap.

[RV Wizard]

I suspect that you will find a bad PTCR (positive temperature co-efficient resistor) (motor starter) and start capacitor for the compressor.