Little problem with air switch. Help appreciated

[SameOld240]

On my 89 (made in 88) 240SX fastback I have a little problem. There is a button on climat control that switches cabin air flow (from outside or recirculating). When the button pushed the little green light on it goes on but air still comes from outside. I understand that there is a motor that switches air flow. But I don't know how it works and where it located. Is there a relay as well? Help appreciated.Thank you