clan

I have a MK3 Galaxy with what seems the usual parking sensor problem the MK1's and 2's had. I have been through all the posts and threads and can find nothing in relation to the MK3. The sensors come on beep for a few seconds and then nothing, as described in all the other poss I can find on the site, except I have checked each sensor, all have power but not one of them clicks. Cleaned them all, and still nothing. I also cannot find where the parking sensor control box is on the MK3, nothing under the passenger seat, and of course no Haynes manual for the MK3. Funny thing is, during the really cold weather when it got past -10 they started working again. I also took the car for a service in my local garage and the man with what he described the best Diagnostic computer on the market could not find any fault. Has me stumped, any ideas.