My 93 300SD will not get any heat in the car.I posted about this earlier and everyone said mono valve.I checked the vaccum lines under hood/dash and everything is connected.I found the mono valve under the hood,it is on the left/drivers side on the front part of the wheel well.There are 5 hoses into it and 3 selonoids,one has 2 wires and the other has 3 wires.I checked the wires and both plugs have 12v coming into them.1 or 2 of the hoses are getting warm,I think these are the ones coming into the valve but I'm not sure.Does anyone know how to by-pass it,is that even possible?Is there a repair kit available?Someone mentioned repairing theirs in my earlier post.I did some loking online and found it listed as an ACC mono valve and boy was it $$$.Any ideas/suggestions?Been a couple of times could have used a little heat.

Auxiliary pump, Mono Valve (if equipped) Heater core Plugged

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

If you pull the power to the valve, it should deliver full heating.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

I tried this over the weekend and still no heat.I guess I need to trace the hoses and see if I can flush/backflush the heater core.The 2 plugins both have power to them,is there any way to check that the valve is working?I guess if I still have no heat after flushing it I'll just have to bite the big one and replace it.

OK, next would be Aquaticedge's suggestion of auxiliary pump. Check for power to the pump, and if it is getting power, is it running? You may have to remove the pump and apply 12v with jumper wires to see if it spins and pumps...

I looked up the aux. w/p and it looks like it is part of the monovalve,is that where it's located? If so I have checked it for power and it has 12v at the plug.If that is it I will remove it and check it to see if it is working.It looks like there are 4 screws holding it to the valve.I probably need to drain down the cooling system a little to keep from making a big mess.