@tyke100 I had the same problem with the fans took the HEVAC out cleaned it up and no luck. Blowers worked in a direct supply. Took the plunge got a 2nd hand HEVAC unit and problem solved. Must be something in HEVAC circuit board in end just as easy to replace the unit. Me and my brother spent a long time checking all the circuits. Don't think 2nd hand HEVAC was that expensive.
could i swap the electronic one for a manuel one if i find one? maybe from and earlier lower spec model?