Xiaowudao (OP), you may want to give Micro Air Easy Start a call. I've called them in the past and was able to speak directly to an engineer.
As for the "flicker", have you tried monitoring voltage and current on both the AC and DC side of the inverter (using a voltmeter and DC/AC clamp-on ammeter) while the load is slowly ramping up to see if there's any irregularities?
Assuming there's no problem with your 3000w inverter, it should have zero problem running your a/c with the MAES installed. Typical inrush current (LRA) on a 13.5k a/c with the MAES installed is usually 15-25a (or 1800-3000w). This load only lasts for a fraction of a second. 1800-3000w is within the inrush capability of most 2000w high-frequency inverters.
Lastly, as a final QC check, I'd suggest placing a high load on your DC system (using the microwave or a/c) for at least 10-15 min. and carefully checking each and every terminal crimp and connection for excess heat. A bad crimp/connection can get hot enough under high DC loads to burn your hand, melt plastic, and possibly start a fire.
Good luck!
