I can't figure out why the fan works fine when the engine is not running but as soon as you start the car the fan won't work. I have tried 2 different ECC units and no different.
It's a 93 850. Any thoughts would be great.

Thanks

 

Probably ignition switch accuracy/slop. The difference between those two situations is the direction the switch came from to get to the "on" position. You can convince yourself by moving the key back some more while it's running.