Help Please!: Heater not working on a 190

Hi - I have a had this 190e for 5 years now - when I first got it, the heater didn't work (fan was ok, just no heat). I left it with the Merc specialist to fix. They said that the vacuum tubes on the controls were
loose - presumably they meant the rotary controls on the dashboard? The book (Haynes manual) says that you have to take the whole facia off to fix this - I'm sure they didn't do this (absolutely no sign of it having been removed) - anyone know how they got at these tubes? (reason is that there is no heat coming through again!). Or might it be another problem? I think the heater matrix is ok, because you can get a small amount of heat from it. any suggestions gratefully received! Cheers Andy Bristol - United Kingdom
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please check if the tube going from the watercolling-system to the heater is hot. If not: a) Maybe no waterpump-circulation b) clogged up - needs cleaning with ... citric acid.
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It is usually the failure of the aux. water pump that caused no heat to the cabin... touch the heater hose that goes from the pump to the cabin... if it is lukewarm... then it is bad. If it is hot, then you got enough heat/pressure from the pump.
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