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Registered
1978 450SL
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11 Posts
Discussion Starter #1
OK I changed out my blower motor & Thank you very I could not have done it without you guys so thanks again But...................

Now I have no heat there's no coolent flowing through the heater core, I have flushed the core it's fine, but I still have a hot intake & cold outtake, ok I'm lost any ideas?????

Thanks Guys
Greg
 

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107
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420 Posts
Sounds like the heater valve, vacuum check valve or heater vacuum unit are not working due to vacuum loss. Keep the heater valve open manually (or a plastic tie) to ascertain faulty component.



 

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Registered
1973 450 SL
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1,126 Posts
Check out this bad boy. It should open and close the coolant flow as you turn the heat on and off. Click on image to enlarge.
 

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Registered
1978 450SL
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11 Posts
Discussion Starter #6
I went through the engine & could find anything that matched I'm posting what I have does this help????
Greg
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,328 Posts
Nope. That won't work. Hit add reply. scroll to manage attachments. Hit browse and find the picture you want to post. Hit open then upload.
 

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Premium Member
2010 Mercury Milan Hybrid, 1993 BMW 325i convertible
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6,077 Posts
Um, guys? He's got a 1978 - that's ACCII, so the parts you're showing him don't exist on his car, and wouldn't help him if he had them.

Greg - welcome to ACCII hell. Your car has the earliest version of the automatic climate control system. Mercedes licensed the technology from Chrysler, and it was bad technology even when it was installed.

You have four choices:
1) Replace the servo and amplifier in your car with new ones. This will cost you about $1700 every two years or so. They won't last, so you'll be replacing them regularly.
2) Replace the servo and amplifier in your car with rebuilt ones. This will cost you about $600 every two years or so. They won't last, so you'll be replacing them regularly.
3) Figure out a way to completely change the system. Unknown cost, and unknown reliability. Kinda depends on how good you are and how deep you want to dig into the murky depths of the ACCII setup.
4) Replace the servo and amplifier in your car with a modern digital replacement. This will cost you about $700, and should last for as long as you own your car.

http://unwiredtools.com/accii.asp

I started trying #2, gave up after a few tries, then switched to #4. I've been happy ever since, and this morning had the heat cranked up to 80 on the way to work. Nice and toasty warm.
 

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Premium Member
2010 Mercury Milan Hybrid, 1993 BMW 325i convertible
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6,077 Posts
If I did this correctly the PIC of my engine should be attached
Well, not so much the engine as the servo and auxiliary pump. ;)

But yes, that is 90% of your headache right there. If you take that apart carefully, you'll find a complex rat's nest of mechanicals that control the vacuum to the vents, and the coolant flow that allows heat into the interior of your car. You'll also find a gummed up mess where one or more of the parts in that thing decided to take a dump. It's pointlessly complex, unnecessarily delicate, and badly designed from the beginning. There's no hope for it, and there never was.

The Unwired Tools replacement (that I can't recommend highly enough) takes the place of that tower, simplifies the connections, and provides reliable climate control for your car.
 
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