Ok you should see a 12v signal for a short time on the blu/blk wire pin 1 on the mode control motor(when you hit defrost and not already in the defrost mode.Remember the connector view is from the back side of the connector.

 

Control is intermittent, one day it was switching(all modes) the next it is stuck in floor/panel. Mode is changing on display just not changing vent position.

From looking at pic, there is no relays, just the climate control unit and mode control motor. With signal be sent between them?

Thanks for all info, I have not had chance to check wiring (working) off tomorrow, will check in the morning

 

Correct no relay so it has to the the motor or the control unit or a loose wire.