Delta fan control problems!!!

What brand of fans?

Something that sometimes happens is that two small fan motors have a huge start up draw (larger than even our fan). And the draw can even be unequal because one blade might have a cannister motor and one might have a pancake motor (this is fairly common). The controller will see this huge start-up draw as a short to ground and the controller shuts down. A simple filter can take care of the issue.

Have you tried turning on the AC to see if the fans try to spool up to 50%? It's a nice place to start because you eliminate the temp probe from the system.

Any more info you can provide might help. Also, it goes without saying that attempting to contact Brian is a wise idea. He's as sharp as a tack.

Good luck.

Just run a fused jumper wire from the battery to the AC input wire on the controller. This test takes 20 seconds to do and will help get the diagnostics going.

FWIW, Brian is a one-man operation AFAIK and he has a day job. Emails can be easier for that reason.