Putting engine under tray back on CORRRECTLY!!

Hello, I know there are thousands of threads on the freelander undertray, but I cant locate anything about putting it back on correctly. After I serviced mine and got it back on, I started to get a really bad noise from the demister when I switched it on. It was ok in all other modes, footwell, footwell and vents, vents, BUT windscreen demist it made the noise.

My local garage sorted the issue for me, but he said it was how I had put the under tray back on!! He mentioned a certain uniformed way of placing the the front flaped pieces of the tray back in or the fan motor or thingamy jig thing gets stuck on it????????????????

Obviously I am confused and am due to service it again, so I want to make sure I dont suffer the same issues again.

Ay help please

When the on screen demist option is selected (later Freelander 1's) I think the air con will be running. Did the flaps rub against the air con pulley?

you could test this by turning the air con in the normal position (not demist) and see if the noise starts with the aircon on and stops with it off

had this twice with mine