83 300SD---Heater Won't Turn Off...Need HELP!
04-08-2006, 05:58 PM
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1983 300SD
83 300SD---Heater Won't Turn Off...Need HELP!
This car is new to me, and I am a first time mercedes-benz owner (but I am not new to diesels, especially VW 
). My problem is that the heater will not turn off. The buttons are not engaged, yet there is heat coming from the vents. This wasn't a problem a few weeks ago, but it is spring in San Diego and I am dying in the heat! Is there something I am missing? Or am I just going to have to pull the heater core(?) out? Any help is appreciated greatly. Thanks.
). My problem is that the heater will not turn off. The buttons are not engaged, yet there is heat coming from the vents. This wasn't a problem a few weeks ago, but it is spring in San Diego and I am dying in the heat! Is there something I am missing? Or am I just going to have to pull the heater core(?) out? Any help is appreciated greatly. Thanks.
04-08-2006, 06:36 PM
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1983 300SD
i'm new to this forum stuff...i usually do all my talking on aim where its instant..not this "posting" stuff... i suppose i will take the heater thing out...but now there goes my defrost in the mornings. oh well, its spring break, I dont have to get up early for a while...
04-28-2006, 12:17 AM
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99 E300 TD, F350&ExcurDiesels
W126 Heater Fix (monovalve)
I'm near San Diego. I hope you haven't baked to a crisp yet (re. your early Apr 06 post).
I'm surprised nobody has quickly jumped in and answered this.
You likely have a bad "mono valve". This solenoid valve ICW electric pulses from your climate control unit controls the flow of hot coolant to your heater core. The rubber diaphragm in the valve eventually goes bad or the valve sticks open (or closed then no heat) either way your climate control unit can't regulate the heat and you have constant "on" heat.
This is a 10 minute job max once you have the part in hand.
You can get a new valve (repair kit) and replace it yourself for ~$43. I've had great success w/ Shane at importec.com you need part number R3023-15174 "Mono Valve Repair Kit." Good prices and fast shipping (free if $50 or more order - e.g. get an oil filter and the valve).
The valve is located just inboard of the battery and below the bottom of the center windshield area. You unplug mono valve harness connector, remove 4 screws, swap out the old/new valve, reinstall the screws, reconnect harness, check for leaks and you're good to go.
"Cool" you now say!?!?!
I'm surprised nobody has quickly jumped in and answered this.
You likely have a bad "mono valve". This solenoid valve ICW electric pulses from your climate control unit controls the flow of hot coolant to your heater core. The rubber diaphragm in the valve eventually goes bad or the valve sticks open (or closed then no heat) either way your climate control unit can't regulate the heat and you have constant "on" heat.
This is a 10 minute job max once you have the part in hand.
You can get a new valve (repair kit) and replace it yourself for ~$43. I've had great success w/ Shane at importec.com you need part number R3023-15174 "Mono Valve Repair Kit." Good prices and fast shipping (free if $50 or more order - e.g. get an oil filter and the valve).
The valve is located just inboard of the battery and below the bottom of the center windshield area. You unplug mono valve harness connector, remove 4 screws, swap out the old/new valve, reinstall the screws, reconnect harness, check for leaks and you're good to go.
"Cool" you now say!?!?!
Last edited by 300SDTURBOS; 04-28-2006 at 12:20 AM.
