w202 heat/vent issue

[pinkaroo]

I have a W202 C250 TD registered in 1999. It has started allowing hot air to be emitted from the windscreen vent and selecting the lower vents on the climate control and setting the fan to a higher speed setting just causes hot air to be emitted faster from the upper windscreen vent and nothing comes out of the lower vents. Is it the old duovalve again I need to check for 12v pulses or something else? I have noticed turning off the climate control does not elicit the usual sound of a valve closing? Thoughts and ideas greatly received. Two recent events which may have contirbuted are a main dealer B service and me taking the wiper assembly off to fix the old juddering wiper/reset the park position. Have I disturbed a vacuum pipe?

 

[television]

Hello and welcome.. I think that you may have disturbed a vacuum pipe

part of it is here

http://www.detali.ru/cat/oem_mb2.as...GM=717.460&CT=F&cat=44V&SID=80&SGR=080&SGN=04

 

[pinkaroo]

Thanks Malcolm, Is that assembly under the dash where the pollen filter is housed?

 

[television]

Thanks Malcolm, Is that assembly under the dash where the pollen filter is housed?

Yes that is all under the dash,,you may hear a hissing sound under there if a pipe is off