As has been stated, the aux pump (which is generally useless) is not separately fused, unless you consider your pushbutton unit's circuit board to be a large fuse. And that's what it will become when the pump goes. Best thing you can do for it is to unplug the pump.

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David Bruckmann, Oakland, CA

Current:
66 Citroën DS21
72 MB 280SEL 4.5
73 MB 450SLC
76 Citroën 2CV6
76 MB 300D
79 MB 300SD
Past:
70 Citroën DS21 (170kkm)/71 Citroën DS21 (137kkm)/72 Citroën DS21 (502kkm)/78 MB 300D (1,200,000 km-ish)/79 MB 300D (425kkm)/79 MB 300TD (260kkm)/81 Citroën 2CV6 (120kkm)/88 Merkur XR4Ti (209kkm)/81 Peugeot 505 GRD (350kkm)/84 MB 300TD (385kkm)/85 Toyota Camry (330kkm)/86 Renault 9 1.7L (155kkm)/02 Golf TDI (74kkm)

and then you'd have no control over the temperature in the cabin but you'd have a nice el cheapo repair.

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________________

punkinfair

Having intermitent heat issues with our W123. I have had the MV apart and it looks ok if memory serves. I will check it again. This is an expensive little bugger.

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85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

I just replaced my monovalve. The results have been amazing. Took less than five minutes.

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84 300D, 303K
71 MGBGT, ?K
96 GMC C1500, 115K

Old thread, I'm dealing with this now.

I replaced my monovalve about a year ago with an MTC unit. The original was toasted.

Now I've got heat only, with cooler air at speeds. I did notice coolant leaking from the bottom of where the valve would sit. Now I'm thinking I may need an entire new assembly.

Will also look more into the aux pump as well.

The MTC unit is a known bad part. Unfortunately the OEM cartridge shot up in cost about a month ago, so have deep pockets. Don't waste your money on the MTC unit, it will only bring you tears (and a cold car)

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Scavenge as many as you find in the yards. They are almost free there because the yard people don't know what they are. I'll get the whole thing next time because my spare body is MIA.

You may have to pull up on the center to see the tear in the diaphragm if you don't know what you're looking for.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I have a spare and I'm keeping it close.

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84 300SD
85 380SE
83 528e
95 318ic

This morning I replaced a 1year old MTC with a new Mercedes part. Problem solved.

I have also been through the mono valve drill. Two things:

1. Replace with Mercedes. The Mtc does not work, and the common symptom is no heat at engine speed much over idle.

2. Be very gentle unplugging the wire to the solenoid. The pins broke on mine, and I had a hard time finding a plug or solenoid without broken pins. In fact, my woes started with broken connector pins. While dealing with that, I decided to throw in the new mono valve I had (MTC). I finally got a working solenoid from a parts yard with the wires cut so the plug does not have to be unplugged.

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1985 300TD. 378,000 daily driver

The inserts are now available from Mercedes. The aftermarket brands usually don't work very well - at least in my experience.

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Will



72 280SEL
85 300CD 288k
00 E320 Wagon 4-matic 100k
11 E350 Wagon 4-matic 45k

73 VW Westfalia Camper
67 VW Westfalia Camper

66 Porsche 912

I said **** it, bought this: Klima Design Works | Monovalve and Coolant Circulator Pump Eliminator / Upgrade Kit

We'll see how it does.

That is pretty cool. I wonder how that would work for the Klima II ?(EVIL Servo)

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All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

Hopefully it works well. I've seen people saying they can source everything in the kit for cheaper but for the time I'd spend, $100 seems like a pretty nice deal for everything it claims to do and the parts I won't have to replace now.