My first guess was the air cond is not an inverter type, so the compressor start up current is between 7 and 10 times the run current ...... 11.5kw or 11500w peak that can be maintained for 30 secs min, but reading through the tech specs for the Harrier lite and the Harrier Plus both use inverter technology, yet for some reason the bigger capacity unit uses less power ...... so there must be some cheapening of the electronics in the Harrier Lite, maybe they don't unload the compressor and allow it to freewheel before it starts pumping ..... who knowsvolts times amps. 220V, 7.5 amps. electric 1650 watts.
As far as the inverter, what model number and brand? Not all inverters are created equal ...
We had a customer arrive for the pre install check over and was excited telling us about the 240vac fridge freezer she bought and the bargain Kings 3000w inverter. The fridge only draws 9.5 amps once it's running, 120w, yet the 600w inverter she has screams on startup and shuts down. Plugged into the 3,000w inverter, no problems, but a 100 amp plus draw to start up the compressor, 1200w start up, so in that case it was 10 times the run current. 1200w was no problem for the 3,000w inverter, but it draws 1.5 amps on standby, that 36 Ah per 24hrs just to have it turned on, so the 45 Ah per 24hrs the fridge would use now has another 36 Ah added to it, so now it's 80 Ah to power a 118ltr fridge
A closer look at the inverter and the label is very carefully worded, 3,000w DC to 240vac power inverter .... the draw is 3,000w, not the output
The fix for your set up, you need a 3,000w output inverter with a 3 times the capacity peak load that can be maintained for 30 secs or more. That means either a W7 / W10 cheap big lump of a thing like this eBay item number:373846458155 might not enough to start that air cond up, maybe a Victron 3,000va multiplus with the big toroidal transformer ( https://www.iqsdirectory.com/articles/e ... d%20losses. ) because the big transformer can carry a big overload for a short period, but not the Victron Multiplus 2 because it doesn't have the massive transformer.
Roof top rattlers no matter what technology is used, take more power to start up and run than a household 240vac split system unit does, but they still demand the peak power a non inverter compressor unit does when at peak load when trying to rapid cool or rapid heat an area, just that it can drop back on the load is the econ or night setting is used, it just takes longer to reach the selected temp ....
T1 Terry