When attached Unit won't start

[GoodnessJSON]

Hi all, I tried to apply this project to a MHI DXK12ZSA-W. Everything went fine, but when I tried to operate the unit it wouldn't start and appeared almost like it had no power. Multiple power cycles, checking cables and they all had the same result.

I removed the Arduino and the AC immediately started to work. Has anyone else seen this? Is it a new development?

[warfuric]

Yep - same.
On a pair of SRK25ZSA, my devices power up under 12V benchtop power and connect to Wifi, but installed in the unit the AC units don't turn on when plugged into the SPI.
I'm contemplating the https://github.com/absalom-muc/MHI-AC-Ctrl project, or just getting the OEM wifi modules.

[deividasjuskevicius]

Hi all, I tried to apply this project to a MHI DXK12ZSA-W. Everything went fine, but when I tried to operate the unit it wouldn't start and appeared almost like it had no power. Multiple power cycles, checking cables and they all had the same result.

I removed the Arduino and the AC immediately started to work. Has anyone else seen this? Is it a new development?

It is happening because +12V and GND are switched on your connector, if you closely compare wiring in the photo and yours, you will notice that connector is reversed