heater control valve always on...

I have a problem with my 2001 2.2CDI 413. The heater control valve stays on and get extremy hot no matter what is turn on or off.

When the sprinter is turned off and rest isnt on the soleinoid is still powered and drains the battery at a current of 1.1 amps. This over time makes it go flat.

Also when we took it away over newyears the heating was always on to the cabin so we unplugged the soleinoid but later got a check engine fault light and it went into LHM. Turned it off for 15min then started and drove home.

Has anyone got a wire diagram for the heating system? or could tell me what each terminal is ment to be for on the control panel?

Have a search through using the drop down in the blue bar above. Could also be a failed control cable - there's a weakness in the way the inner and outer cables are put together using just a plastic boss at one end. It fails then the inner can't move independently of the outer. Result is no available adjustment, valve under the dash top can't move. It's a bit of a pain to strip the dash out but you only need take the centre / heater control panel out to get a look at the end of the cable. Go carefully with the heater control panel removal as there's not much free cable (it unhooks at the back).

It doesnt have a cable its electric

My '03 service manual says my heater solenoid valve is open (coolant flow and heat from the heater) when not powered. It needs power to close (no heat). Your description seems to say yours needs power to open since there is apparently no heat when the valve is disconnected. If that's right, then yours is being powered by the automatic temperature control (ATC) unit when it shouldn't be, suggesting an ATC malfunction.

I've found a bunch of info to start looking into the electrical problem, going to check it out now. Will update as I progress. Thanks.

I have 2000 311CDI. Like talkinghorse43 noted the valve is open without any power (connector removed). In my 311CDI the water valve (solenoid) is sometimes living its own life. It is sometimes switching on and off, even when the ignition etc. is off and the car is locked. Local MB service identified the fault into the temperature (switch) control unit, which is directly controlling the valve, but the price for the control unit would have been so high that I did not let them change the unit and the problem got not yet removed... I am planning to remove and check the unit and try to make my own investigation into its connectors and internal life. LYNTONM, did you already got the problem resolved?

jtm-sprinter said:

I have 2000 311CDI. Like talkinghorse43 noted the valve is open without any power (connector removed). In my 311CDI the water valve (solenoid) is sometimes living its own life. It is sometimes switching on and off, even when the ignition etc. is off and the car is locked. Local MB service identified the fault into the temperature (switch) control unit, which is directly controlling the valve, but the price for the control unit would have been so high that I did not let them change the unit and the problem got not yet removed... I am planning to remove and check the unit and try to make my own investigation into its connectors and internal life. LYNTONM, did you already got the problem resolved?

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I have similar problems. Sometimes I get heat even with the temp dial turned all the way to cold, sometimes the a/c will not engage and sometimes it will. Turning off the ignition and turning it back on again often fixes the issue. So I'm thinking it's a balky control unit. Price to replace it is more than having a kid, so perhaps i will just live with it as yet another common sprinter gremlin. I was thinking of taking the panel apart and checking for obvious bad connections, let me know if you find anything that looks user-fixable.

I have the same problem, i have dismantled much of the dashboard, including removing the instrument panel, have lubricated the cables and all move freely, but for the life of me I can not see how I can acess the pulsed heater valve without stripping out the entire under dash panel.

I have removed the insulation covers from the heater A/C plastic assembly but see no way to remove the top cover to access the valve from the engine side

Can anyone please tell me how I get to the valve to check its operation, or if it is dead, replace it.

johnb said:

I have the same problem, i have dismantled much of the dashboard, including removing the instrument panel, have lubricated the cables and all move freely, but for the life of me I can not see how I can acess the pulsed heater valve without stripping out the entire under dash panel.

I have removed the insulation covers from the heater A/C plastic assembly but see no way to remove the top cover to access the valve from the engine side

Can anyone please tell me how I get to the valve to check its operation, or if it is dead, replace it.

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What van do you have (year, etc.)? My '02's heater valve is accessible and visible in the engine compartment, right next to the blower housing, just above and to the left (looking to rear from front) of the engine.

talkinghorse43 said:

What van do you have (year, etc.)? My '02's heater valve is accessible and visible in the engine compartment, right next to the blower housing, just above and to the left (looking to rear from front) of the engine.

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Similar in my year 2000 model. This valve is visible in the engine compartment. Unfortunately I have still not taken the time to check this problem/control unit, as the valve in my 311CDI has lately been without this problem...at least I believe so. I assume that at least the problem in my model might be related to some kind of a grounding problem in the control unit, because this problem is somewhat randomly appearing/disappearing. Whether the ground wiring is properly connected....or some bad soldering point, I have not yet checked.

Is it really so that not a person (reading these forum messages) yet found out the reason for this problem? As I did not have time and also failed to have proper knowledge for dismantling/removing the instrument panel without breaking it.....I just added a relay with its ON/OFF contacts in between the wire controlling the valve. And powering the relay so that it is ON, when the entire car power is switched on. Helped to avoid the valve using power and running battery empty, when this MB Sprinter is not in use. Let the obviously faulty control unit live its own strange life i.e. the problem still exists somewhere there......and I would like to know/fix it.

Old post but i'll add my experience. I like your relay solution. That is a good idea. Perhaps you should get a new heater control valve too. I wonder if you unplug the climate control unit in the car if the voltage will go away from the valve? THen you know its a climate control unit problem in that respect. But may have a valve problem too. My friends 2003 Sprinter 2500 has a problem with always having hot air even though it is turned to cool and the ac is on. We just replaced the control unit inside the car -- had it rebuilt on ebay for 99.00 with a lifetime warranty. That let him adjust the temp but it still is letting heat come through even though its on cold. So now we ordered the heater control valve from autohausaz.com . It is 116.00 . This is a common problem with mercedes ever since I've been driving them the last 15 years -- 1980s up. My 2006 cdi has a similar common problem. Sometimes it wont' blow hot no matter what temperature but mostly it works fine. I ordered heater control valves for both of us. Mine was only 46.00 . The sprinter is 116.00 . Seems sprinter owners are getting ripped off.

Depending on where the valve is located and where you live, a 3 way manual ball valve is a good solution. Turn it off in the summer and on a little in fall and full on in winter … I've done that before. In TN though it can be 70F one day and 30F the next in the fall and winter so its not ideal.

I hope the 116.00 valve fixes his problem and its nothing more complicated. I'll let you know.

I will add that on the sprinter and my 2006 mercedes e320 cdi , there are no fault codes at all . This leads me to suspect the control valve at it is just kind of a dumb solenoid valve.