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  #16  
Old 12-02-2006, 08:30 PM
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Well, some progress made today. I cut the two wires that feed power to the servo motor installed a DPDT switch. In 1 position the switch allows "as it was" operation of the servo; in the other position the polarity is reversed and the servo drives to full heat! The only problem now is since the blower operation is dependent on the servo position none of the blower on functions will work except DEF. Oh well, at least I have heat now until I can get the full cool servo control mess figured out.

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  #17  
Old 12-02-2006, 09:23 PM
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Hi there,
As I stated in my previous post, the blower operation is NOT dependent on the servo for it's on/off function, the MAIN vacuum sw. #19 is responsible for turning on the blower in all positions except the defrost position, and if you don't have enough vacuum to operate sw 19, it just "aint gonna work, no way, nohow." Please reread my previous post carefully and check the items I listed for your fix. The servo IS responsible for the blower SPEED control as well as modulating the heat in the normal operating mode. Note that vacuum switch #35, a bimetallic switch on the bottom of the servo, is monitoring the engine temperature, and won't let vacuum sw 19 "make" until the engine water temperature is at or above 104 degrees, which with a good vacuum system will cause the blower to then turn on. You can bypass switch 35 by connecting those two vacuum lines that go under the servo together, but you will loose the delayed blower on feature.
With the ignition turned off, you should have +12 volts at pin six of the amplifier, which should cause the servo motor to park in the P position. If you don't have it, fuse 12 is blown. It's in a barrel container, not on the main fuse panel.
I do have the factory manual for this climate control system, and the info I'm giving you is straight from the manual...
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #18  
Old 12-03-2006, 01:04 AM
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Quote:
Originally Posted by Richard Wooldridge View Post
Hi there,
As I stated in my previous post, the blower operation is NOT dependent on the servo for it's on/off function, the MAIN vacuum sw. #19 is responsible for turning on the blower in all positions except the defrost position, and if you don't have enough vacuum to operate sw 19, it just "aint gonna work, no way, nohow." Please reread my previous post carefully and check the items I listed for your fix. The servo IS responsible for the blower SPEED control as well as modulating the heat in the normal operating mode. Note that vacuum switch #35, a bimetallic switch on the bottom of the servo, is monitoring the engine temperature, and won't let vacuum sw 19 "make" until the engine water temperature is at or above 104 degrees, which with a good vacuum system will cause the blower to then turn on. You can bypass switch 35 by connecting those two vacuum lines that go under the servo together, but you will loose the delayed blower on feature.
With the ignition turned off, you should have +12 volts at pin six of the amplifier, which should cause the servo motor to park in the P position. If you don't have it, fuse 12 is blown. It's in a barrel container, not on the main fuse panel.
I do have the factory manual for this climate control system, and the info I'm giving you is straight from the manual...
Okay, thats good stuff. It explains why the blower isn't coming on in anything except DEF. Vac switch 35 should have made & allowed #19 to operate because I had PLENTY of hot water heat once the beast warmed up. At least my hunt has narrowed. Thanks again for your response AND patience. Update to follow, I'll check into it tomorrow. Thanks again!!
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  #19  
Old 12-03-2006, 06:38 PM
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I too have been struggling with that damn climate control system. Redid the entire vacuum hose routing, rebuilt the servo, replaced amplifier. The servo seems to be working OK and the temperture thumbwheel seems to regulate the heat settings OK. It took awhile to get it all working correctly, specifically the sync of the servo gearing to the water valve, it's working but some documentation would be helpfull to fine tune.

A few questions though:

What kind of grease do I use on the servo gears and internals? Looks a little dry after handling so many times.

Is there a procedure to sync the water valve to the servo arm position? I tried a bunch of different way's and it finally started to work properly. I almost gave up in disgust, but my last attempt seems to have worked.

Anyone have a servo assembly diagram? Would come in handy for a second one I might rebuild.

I might post this as a new topic as I'm sure many people have been here before.
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Last edited by 450slcguy; 12-03-2006 at 08:54 PM.
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  #20  
Old 12-04-2006, 10:29 AM
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Quote:
Originally Posted by 450slcguy View Post
I too have been struggling with that damn climate control system. Redid the entire vacuum hose routing, rebuilt the servo, replaced amplifier. The servo seems to be working OK and the temperture thumbwheel seems to regulate the heat settings OK. It took awhile to get it all working correctly, specifically the sync of the servo gearing to the water valve, it's working but some documentation would be helpfull to fine tune.

A few questions though:

What kind of grease do I use on the servo gears and internals? Looks a little dry after handling so many times.

Is there a procedure to sync the water valve to the servo arm position? I tried a bunch of different way's and it finally started to work properly. I almost gave up in disgust, but my last attempt seems to have worked.

Anyone have a servo assembly diagram? Would come in handy for a second one I might rebuild.

I might post this as a new topic as I'm sure many people have been here before.
I found the vacuum leaks causing the fan not to run in any position but DEF; now it works. BUT......... the servo still drives full cool in auto regardless of thumbwheel settings. I've got yet another amplifier on the way to me in the mail. Hopefully it will solve this. I would like to know how to rebuild the servo also. Can you provide info on how you did it? Maybe dialectric grease would work for you on the wiper. Might need a higher temp rated grease on the lower servo motor gear. A guy on eBay that rebuild these wouldn't share his info.
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  #21  
Old 12-04-2006, 02:10 PM
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Quote:
Originally Posted by jjewell View Post
I found the vacuum leaks causing the fan not to run in any position but DEF; now it works. BUT......... the servo still drives full cool in auto regardless of thumbwheel settings. I've got yet another amplifier on the way to me in the mail. Hopefully it will solve this. I would like to know how to rebuild the servo also. Can you provide info on how you did it? Maybe dialectric grease would work for you on the wiper. Might need a higher temp rated grease on the lower servo motor gear. A guy on eBay that rebuild these wouldn't share his info.
Basically trial and error approach. I disassembled my old one to see how it worked. Then I bought an old one on ebay and between the 2 put 1 together. The hard part was to sync the "wiper arm" with the plunger valve. Not sure if I could explain what I did to get it to work, basically the opposite of what you would think. In the park position of the arm, I unscrewed the valve to the up position(heat valve open) then assembled the unit. Also there is what looks like a potentiometer on the upper contact plate with a mesh gear to the servo drive gears. Fiddling with that in conjunction with the wiper arm and plunger valve seems to have done it. My original thought was to have the valve closed in the park position, but that didn't seem to work. I don't know if any of this helps you but it's the best I can do. Information is very scare on the inner workings of the servo and some documentation is definitely needed. Hopefully mine will continue to work through the winter especially since in will be garaged most of the time.
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Last edited by 450slcguy; 12-04-2006 at 02:20 PM.
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  #22  
Old 12-04-2006, 06:50 PM
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Hi there,
Congrats! Now that you have an operational vacuum system, click on the Unwired Tools ad at the top of the page and read all about their digital servo replacement upgrade kit, which replaces the mechanical servo completely, and installs a much cleaner microprocessor controlled climate control system in it's place. It's spendy, but gives the car a much more precise control of temperature, won't run your battery dead, like the mechanical servo can, etc... I installed one about a year ago, and it works GREAT! Much better than the mechanical setup, and a lot cleaner install. I installed my unit behind the glovebox, with the new heater valve outside, similar to the '82 and newer SL's.
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #23  
Old 12-04-2006, 09:59 PM
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Quote:
Originally Posted by Richard Wooldridge View Post
Hi there,
Congrats! Now that you have an operational vacuum system, click on the Unwired Tools ad at the top of the page and read all about their digital servo replacement upgrade kit, which replaces the mechanical servo completely, and installs a much cleaner microprocessor controlled climate control system in it's place. It's spendy, but gives the car a much more precise control of temperature, won't run your battery dead, like the mechanical servo can, etc... I installed one about a year ago, and it works GREAT! Much better than the mechanical setup, and a lot cleaner install. I installed my unit behind the glovebox, with the new heater valve outside, similar to the '82 and newer SL's.
I have been considering getting one of them. Do you have the newer version? It looks like the best way to go long term. By the way, thanks for your advice!!
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  #24  
Old 12-05-2006, 12:36 AM
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When I ordered the digital servo unit, it came with the original unit, which worked ok. However, when I learned they had a newer release out, I called them, and they sent me the new version free of charge for returning the old one! It really works well, controls the fan speeds just like the original servo, switches between heat/cold, and has much more precise control of the temperature than the original unit.
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #25  
Old 12-05-2006, 07:45 AM
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Quote:
Originally Posted by Richard Wooldridge View Post
When I ordered the digital servo unit, it came with the original unit, which worked ok. However, when I learned they had a newer release out, I called them, and they sent me the new version free of charge for returning the old one! It really works well, controls the fan speeds just like the original servo, switches between heat/cold, and has much more precise control of the temperature than the original unit.
Sounds like the best bet to do this since I'm going to be keeping this car. Still gonna have to dig into the wiring to find the apparent short in my sensor circuit; even the digital setup won't work until that is resolved.
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  #26  
Old 12-05-2006, 09:34 AM
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The digital servo comes with two new sensors that replace the ones in the car. The existing sensor circuit has too many flakey connectors in series with the sensors, the new sensors are hard wired to the servo for a more accurate reading. So the only part of the circuit that remains is the temperature control knob resistor. Also, when I installed my digital unit I cleaned up the vacuum lines that go through the firewall. Since the digital servo controls the pod diaghrams with new vacuum solenoids, I located them inside the car, so the only vacuum line that goes through the firewall is the one that controls the water valve solenoid. Much cleaner looking!
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #27  
Old 12-12-2006, 08:17 AM
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3rd times a charm- replaced the amplifier AGAIN & now have full auto control. NEXT is digging into the vac pods- I know the DEF one is leaking & when I go to bi-level I can actually hear what sounds like a fluttering vac leak. getting there.................At least it works in auto now

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