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77 450SL, 79 450SLC 5.0, 67 250SL, 61 190SL, 61 190, 62 180;Others:www.cardomain.com/id/challenger_7
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33 Posts
Discussion Starter #1
Hi All
I am new here but already getting much appreciated help. What a fantastic forum :thumbsup:
I recently purchased a 026 SLC and very happy with most of its state.
However, the A/C system, although cooling very well, is in a terrible state. The previous owner's mechanics have really messed it up.
Anyway, so far I have replaced the servo and aux water pump, and now trying to make sure the water and vacuum hoses are correctly installed, because the flow of air is not correct as per the push buttons' positions, and I am not getting heat in order to regulate the temp.
Can anyone lead me to a diagram that shows the water hoses connections, and if available, the vacuum hoses too?
Any help will be appreciated
Cheers
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,224 Posts

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Registered
77 450SL, 79 450SLC 5.0, 67 250SL, 61 190SL, 61 190, 62 180;Others:www.cardomain.com/id/challenger_7
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33 Posts
Discussion Starter #3
Thank you nobby for your warm welcome and the direction you pointed me to.
I will do as you suggest.
Cheers
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,266 Posts
Hi and welcome to the forum. If you're not getting heat it's probably one of four possibilities.

1 The monovalve (the hot water valve) is kaput- fairly common.

2 Someone has blocked off the water line to the monovalve to stop all heat.

3 The vacuum line to the monovalve from the control switch is not connected properly at the valve, or not holding vacuum ( sometimes the lines crack)

4 The switch that controls the monovalve via the vacuum line is disconnected or not working.

I would suggest checking 1 and 2 first- mostly because they are the easiest. The valve has a little lever which moves to open and close off the water flow. You can also check to see that the rubber hose from the water valve is connected to the brass tube from the heater box, and the exit tube on the other side is also connected. If the valve is properly hooked up and the tubes are connected then it becomes more difficult. Check those first.
 

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Registered
77 450SL, 79 450SLC 5.0, 67 250SL, 61 190SL, 61 190, 62 180;Others:www.cardomain.com/id/challenger_7
Joined
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33 Posts
Discussion Starter #5
Thank you Aussiemerc for your welcome and advice.
Actually, both my servo (hot water valve) and aux heater pump have just been replace with the original type (not quite like the photo you posted). See my photos.
But I suspect the previous owner's mechanic has messed up with the vacuum lines, which is not allowing the servo to direct the hot water correctly.
My mechanic has located two diagrams for the vacuum lines, both of which are meant for the same car, but they differ substantially (photos attached).
Can anyone verify which diagram to follow, or where to get the correct one?
My car is a European version.
Cheers
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,266 Posts
Sorry about that, mine is completely different. I didn't realise 450's came in a 5 litre. Good luck!
 
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