[jeff5may]

grayhawk,

Looks to me as if YMGI is a partner of Hiseer international, formally known as:

Guangzhou Hiseer Air Conditioning Co., Ltd

They seem to be a chinese contract manufacturer who will build whatever (relatively smallish) number of predesigned units with your name on them. It looks like YMGI in America is basically a storefront/marketing headquarters for the USA market.

I perused the YMGI website, and found very little useful information. The good stuff is either not built yet (training, documentation, service & support) or behind a wall you have to apply to get past. My guess is there's not much on the other side of the wall, either.

This company seems to be the norm in the industry nowadays. You must be an authorized service dealer to reach anyone with expertise. Even then, an abnormally painful and thoroughly boring series of conversations must be made with the "wizard" to determine anything.

The "wizard" is careful not to disclose anything to you that would simplify the repair or troubleshooting process on your end. Board or unit level repair is usually prescribed, with plug-and-play results. Sometimes I feel as if the "wizard" has no clue what's wrong, so he just sends the whole unit. Of course, he wants the old one back to diagnose it at his bench.

The good news is that the unit is probably the "house that Jack built", i.e. someone elses' hand-me down parts from prior production runs. Hiseer grabs the guts from a "no longer available" unit line, reflashes the EEPROM with their control codes, and slaps a silkscreen on the unit. Presto! It's now a YMGI!

All you really have to do with these units is look into the guts to find out where they originated. The hardware is designed once, then recycled for as long as economical. As for control codes, source code, or a master program chart, this stuff stays inside the r & d department. It will pretty much need to be reverse engineered.