s280 heater problems

[jonnybhoy67]

Hi i have a mercedes 280 automatic and when i put the heating on hot i only get cold air and i when i put it on front screen heater to clear the front windscreen it doesn't do it it only blows out cold air any idea what this could be?

 

[hmang]

check out your duo valve ,they can stick or fail .
although mine have usually failed to the hot position
worth a look, bit awkward on yours, by wiper motor
give em a tappy tap tap with big screw driver handle

 

[Steve@Avantgarde]

I would check the engine thermostat first and foremost, make sure its opening and getting to 80 degrees on the temp gauge, if not then the coolant cant recirculate as far as the duo valves.