Heater-AC Vacuum Harness Diagram 1993 110 NAS - Defender Source
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  #1  
Old April 29th, 2007, 10:28 PM
R. Kurk
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Richard Kurk
1993 110 NAS #489
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Heater-AC Vacuum Harness Diagram 1993 110 NAS

I have recently found and fixed a troublesome problem with the fresh air/re-circulated air control in my 1993 Defender 110 NAS. While doing that I mapped out the location of the vacuum lines that control the various vents, heater and fresh/re-circulated air components. The workshop manual has no information on this so I have attached the diagram for anyone who might find the information helpful. I have carefully created the diagram from notes that I made as I worked my way through the system and believe it to be accurate, but if someone finds a error please let me know immediately so that I can make any corrections.

Rich Kurk
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  #2  
Old April 29th, 2007, 11:49 PM
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Andrew Najarian
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Thanks! I am not sure if I'll need it or not when I reassemble the dash, but it is certainly great to have!
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  #3  
Old April 30th, 2007, 07:01 PM
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Richard - Thanks for sharing the vacuum line diagram. I've got my dash apart right now so this will be helpful to sort out some things.
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  #4  
Old April 30th, 2007, 10:00 PM
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Doug Walker
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Impressive.

Many thanks!

Doug W.
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  #5  
Old May 1st, 2007, 07:56 PM
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Devin Walton
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Richard,

That diagram is awesome. I'm curious what problem you were having. I noticed that when I have my vent lever in the middle position if I put load on the motor it switches the output (it no longer comes out the vent and goes to the defrost, I think). I assumed that this was a vacuum issue behind the dash.

Thanks,
Devin
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  #6  
Old May 1st, 2007, 09:25 PM
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Richard Kurk
1993 110 NAS #489
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Devin,

The problem with mine was that the fresh air/re-circulated air control would not work. Regardless of where the lever was positioned it was always bringing in fresh air (preferable choice in most situations). After a bunch of troubleshooting looking for leaking vacuum lines, broken vacuum motors, etc. the problem turned out to be easy to fix. The vacuum switch (RTC 7451 on diagram) at the top of the 'Heater Controls' (levers for heat, air, defrost, etc) which controls the vacuum motors for the fresh air or recirculated air was loose. When you moved the lever up for re-circulated air it simply moved the entire switch body and did not press the "plunger" to make the switch function. I aligned the switch and tightened the screws and things work fine. Many hours of my labor but zero parts cost!

My guess is you have a leak or weak vacuum. I noticed when I testing my fix that I could use the lever for selecting fresh air or re-circulated air about two times before the vacuum would run out (engine stopped). When it ran out of vacuum the vacuum motors and the vents would slowly stop somewhere in there travel generally partially open or closed (depending on the intended state). Once the engine was started the vacuum motors would return to their desired/intended state. 1960's vintage Lotus Elan's and similiar vehicles with vacuum powered items such as recessed-flip up lights would have the nasty habit of retracting themselves on long hill climbs where the engine could not maintain the needed vacuum level. I have not gottrn into the other vacuum components (defrost, vent, etc.) but I would expect that the motors and vents would return to a 'no-vacuum' state if the vacuum runs out or is too weak regardless of where the lever is positioned.

I hope this is of some help.

Thanks,

Rich K.
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  #7  
Old May 2nd, 2007, 08:09 AM
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Thanks, Richard. That is helpful and sounds exactly like what's happening.
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  #8  
Old May 2nd, 2007, 01:46 PM
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Nice work!
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  #9  
Old May 5th, 2009, 01:46 PM
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barry f
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I know this is an older post. My yellow vacuum tube broke. Can I fix this with shrink tubing?

Thoughts?

http://www.flickr.com/photos/barryrides/3496236024/
http://www.flickr.com/photos/barryrides/3496234442/
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  #10  
Old May 6th, 2009, 06:32 PM
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Richard Kurk
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Just a suggestion (disclaimer > I have not tried it) is check some place like McMaster-Carr and see if you can find some tubing (semi-flexible but won't collapse rubber etc) that the internal diameter is equal (or slightly smaller) than the outside diameter of the existing broken vac line. Use the new line to patch/bridge the broken pieces. Second suggestion, but it is probably more complex is that I believe you can buy replacement vac lines (by the linear foot or meter) from brit-car.co.uk. I thought I bumped into these on their website in a search awhile back for general 110 AC parts.

Sorry this is not a definitive answer but maybe it is a start.
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  #11  
Old May 6th, 2009, 06:38 PM
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barry f
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Thanks, I think you can buy the vacuum lines. I was looking for an easy way to fix this as i really dont want to take the dash apart again. Then again I need a bulb for my clock. Also I am so sick of ordering stuff online. I want instant gratification.
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  #12  
Old May 6th, 2009, 06:47 PM
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Richard Kurk
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I hear you. I hate to have to stop work on my 110 waiting for parts which it seems are proportionately farther away the bigger the issue. I think Rovers North, Rovers Down South, Atlantic British and most of the UK sources should set up shop in California (dream on).

Good luck. Post a message when you find a solution, I suspect I will need to borrow it at some time in the future.
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Old May 6th, 2009, 06:52 PM
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barry f
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Yeah right now I am waiting on a new relay and resiter for my AC as it only works on High. Of course this was after waiting for a new fan switch to come to my house only to relize it wasn't that. Then I noticed the ripped yellow cable.
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  #14  
Old July 11th, 2009, 08:29 PM
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barry f
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Having some AC issues. I know there are three identical vacuum motors according to the diagram. One for the fresh air outside, one by the passenger feet and then there is one for which vent the air comes out of. Where is this in the car? Do I have to take apart the dash to get to it?
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  #15  
Old July 12th, 2009, 06:50 PM
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Richard Kurk
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Barry,

I have not had any of the vac. motors apart, and it has been quite awhile since I was into the dash space, so I cannot tell you where it is exactly. However, that being said the vac. motor that controls the interior air flow (I think this is the one you are asking about) distribution between defroster/dash vents/heat vents is NOT in the main gray dash area (where the louvered vents are). I believe it is further down in the space below the louvers, where the speakers are mounted, passenger side. I have not had this black padded piece off to gain access so I cannot tell you how to do it. Unfortunately there are no (99% confidence) shop manual instructions for this. From memory it struck me that gaining access to this area would be moderately involved (time consumming without a manual) . It is possible another NAS 110 owner could give you specifics. Sorry I do not know the definitive answer to a good question.

One other comment on the vacuum line diagram I create a few years back. The vac motor that controls the air inlet at the fender does not have a part number on any parts manual I have seen. I can only assume that it is the same part number as the other two. Like you I have purchased vac motors from Rovers North to keep as spares in the event they are needed and I am hoping one will work in this location.

Rich K.
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  #16  
Old July 12th, 2009, 08:22 PM
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barry f
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Thanks Richard.

I have been having some issues with my AC and I figured replacing the vacuum motors at the same time would be smart since I can't get the vents to just blow out the dash. It blows out the defroster as well. Since my blower motor stopped working today though I have another priority.
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  #17  
Old July 12th, 2009, 08:48 PM
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Richard Kurk
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Per the owners manual, regardless of the position of the Air Distribution control there will always be a "bleed". Here is a summary of the manual text:

Control fully up "Air is directed to the windshield with a bleed to the footwell"

Control in central position "This position is used to direct air from the fascia-mounted louvres, with a bleed to the footwell"

Lower position "Air is directed to the footwells, although a certain amount will continue to flow through the demister vents to the windshield"

Everything above in quotes is verbatim from the owners manual. I had the same reaction you are having when I got the 110, I thought something was broken because air was "leaking" (my phrase) through every orifice. So what your experiencing is built it, not a problem, unless the "bleed" is a lot (30-40% of the air volume ? guessing).

I hope this is of some help.

Rich K.

Follow-up Post:

Regarding the vac motor replacement. I almost always replace everything in the vicinity of where I am working ... I hate having to tear something down again. It costs money, but in the long run I think I am saving or at least breaking even on labor (sometimes mine, sometimes the local LR shop).
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  #18  
Old July 14th, 2009, 05:04 PM
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barry f
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My bleed issue is that it comes out the defroster when I have it set to center vents.
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