12VDC 30A circuit breaker tripping

[TexasSkunk]

I have a 2007 Allegro Bay 37 QDB FRED. In the service bay just in front of the door there is a 12VDC 30A breaker labeled " Battery Fuse Block Breaker". One input wire and three output wires. This breaker provides power to the non-ignition controlled fused outputs located in the dash fuse block and to the dash mounted AC fan.
All is good until I turn the dash AC fan on high. A few minutes later this breaker trips. No problem running the fan on low-medium, just when I set to high. Then its "pull over, open the bay and reset the breaker by pushing the little black buttons on the end". This is South Central Texas! I need to be able to run the fan on high!
Is this breaker defective and tripping too soon? (As it runs for a while it obviously is not a short) or do I need to split the output load with 2 20A breakers or replace it with a 40Amp?

All constructive input appreciated.

[Skip426]

I would think that replacing the C/B with a new unit would be the first step.
However you need to consider all possible loads on the circuit.
A similar C/B on my coach provides power , for the entire A/C , operation, dash fan, compressor clutch and condenser electric cooling fan.
Don't know if your Fred chassis uses an electric condenser fan.
Also a little confused by your " non ignition controlled " description.
Surely the dash A/C would be on an ignition controlled circuit.

[wa8yxm]

Use a clamp on DC ammeter such as the Crafstman model I have here, and measure the current... Did that with one of my roof A/Cs that was tripping the 20 amp branch circuit. Confirmed it was the A/C.

Went up and cleaned off the condenser coils

Current draw now closer to label specification (13.5 amps)

In your case. I am guessing bad motor but it would not hurt to pull the blower and inspect for either obstructions to the air flow or damage and also how easily the thing spins.

But I'd use a clamp on meter to measure the draw first.