Heating in 1991 W463

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anu
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I seem to be having an issue with the heating on my 1991 W463 300GEL. When the blower is off and the top and bottom sliders are turned to off (far left) air still leaks out from the top windscreen and footwell vents. Is that normal?

If the heating and blower has been used, then turned off, even if you move the temperature back to cold afterwards (with the blower off) hot air will still leak out from the vents - not cold. It's not a massive amount, but it can be quite uncomfortable on your feet when it's continuous hot air. However if you turn the blower back on, it eventually goes cold, and after that point the air leaking out is no longer hot. 

Does anyone have any ideas of what's going on? (Or even if that's all normal - I'm new to G's!)

The heating valve has been replaced, but I don't know if it could be faulty or it's something with the cables, or the matrix itself? 

Thanks for your help!

Pistonhead
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Re: Heating in 1991 W463

If I have understood you correctly, turning ON and OFF the temperature control; these work as they should do.

Using the air vent sliders is when you seem to have problems. When the slider is turn is in the CLOSED position i.e. left side then the air coming out should correspond to the settings. You have a radial dial for air direction to screen, face, feet or combination mix of one or other.

Air from the round vents by the foot wells always work if I recall correctly, these do not respond to the slider settings nor with the air directional settings.

NOTE: My memory recall is questionable - so I could be wrong.

 

Arnie
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Re: Heating in 1991 W463

Seems like you have a problem with the heater control valve (that controls water flow through the heater matrix) and/or the mechanical links to the sliders. You should definitely be able to turn off the heat.

You'll need to remove the centre panel to investigate 

 

anu
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Re: Heating in 1991 W463

Thank you. So you should be able to turn off the air completely with the sliders to the left? If so then there seems to be an issue there that I need to look into...

 

 

Arnie
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Re: Heating in 1991 W463

Yes, there is a water valve in the heater circuit that should turn-off completely when slider set to Blue (cold)


Also, it should be possible to turn off all the air to the windscreen and foot wells. The two side vents and centre vent have independent controls for air-flow

(Have sent you a PM).