I have a new, out of the box Multiplus 2000, 12V on a test bench setup. Feeding it is 280AH of Lithium @ 13.5V. I start the inverter and it's quiet. I put a load on it via a heat gun and it immediately starts a loud low frequency buzz. The heat gun pulls 70Amps of from the pack measured on the BMS and a DC clamp meter, but Victron Connect shows -43 Amps. All connections are tight and double checked. Wire Gage is correct.
There is also a fan and temperature fault issue. When both fans come on during inverting or charging, they struggle to blow at full speed and emit noise (not wind noise, a fast clicking is the best way to describe it) and the Multiplus eventually goes to temperature fault then shuts down some time after the fault. Before the shutdown, I unplug one fan (top of board, Right Side Fan) and the remaining fan jumps to full speed, as normal, with no clicking sound. I plug the right fan back in and both immdiately go to clicking, slow down and appear to struggle. The fan voltage on the top connector with no load is 8V DC.
Anyone have any ideas?