307 blower works when it wants to!

[notamechanic]

Hi
I am new to this forum

my problem is that my 307 cc blowers seem to work when the car want as apposed to when i'm feeling cold or hot.
i can start the car push the fast window de-mist button or the zircon button or they to turn the fan up and nothing happens i'll try again later and all seems to work.
when we had snow in december i couldn't get heat and now when its hot i can't cool down.

I took it to peugeot whilst under warranty was charge £75 to have a look but they could find nothing wrong.

Would anyone have any ideas?

Thanks in advance for any help.