bosch classixx model no wtv74103gb/07?

i can only get the machine to work on the 40min timed warm
program
it will not work on any other settings which operate much hotter to dry clothes it cuts out after 2 minute???
there are no blockages to vent pipes and they look clear also.
no lights appear or come on ref filter
if i put my hand at back of machine where pipe vents out there is a warm air blowing and it then cuts out??unless on the 40 minute cycle which is not operated via sencers im told??
please does anyone have a idea