Engel shx2000 horror story - engel reliability - not with gennies!

Generator choice is hard, but it was hard to go past the Engel SHX2000. The plan was to run a small air cond unit drawing 500W with it in a caravan. Honda 2 KVa did it with ease and lots of extra to spare. So I bought an Engel. Googled the Engel model even with the words "engel, known problems, faults etc." Felt I'd done my homework. Decided to buy item. Then things went wrong.

1. Bought it, hooked it up to the a/c, and the machine lets out a piercing howling sound.

2. Turned it off, brought it back to the shop, we tested it there with lots of applicances, and all was ok, no howling.

3. Went back, tested it again with a/c, howling started again

4. Rang Engel Customer Service Line. Response: This machine is not designed to run any a/c:s. Our specs say do not run an a/c with it. It's a square wave machine, not pure sine wave (whatever that means...) They said Lots of people who have bought one have called us and said why is the gennie howling with some apps.

5. Rang shop and said can you take it back, I can't live with the noise. And it does not say anywhere in any brochures or ads for the machine, that do not run the unit with any a/c.They said we'll ring State Manager.

6. Rang Customer Service again. This time they said you can run an a/c with it as long as the load is below 1800 W! I said the gennie runs it beautifully, startup goes only to half load according to leds, a/c works but cannot live with the piercing sound from the gennie.

7. Half an hour later, another phone call from them, and on wed i'll be driving a 240 km inc return trip to a capital city to have it "assessed" by an expert company.

I'll let you know how I went.