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There are various ways to attempt flushing a heater core. On past vehicles I've had luck just doing it the garden hose method, forward and reverse, until it runs clear. Blow out with compressed air and/or rinse with distilled water to get the mineral tap water out.
More aggressive methods use a product like CLR, as shown on the South Main Auto youtube channel.
Once you are backed into the corner and heater core replacement is the next step, I'd be willing to try all kinds of things even if they could damage the heater core.
If I were you I would attempt a vacuum fill of your system to rule out air pockets.
can you please show me where the 2 pipes are coming out of the firewall for the heater core? I am trying to find them
Originally Posted by kevm14
There are various ways to attempt flushing a heater core. On past vehicles I've had luck just doing it the garden hose method, forward and reverse, until it runs clear. Blow out with compressed air and/or rinse with distilled water to get the mineral tap water out.
More aggressive methods use a product like CLR, as shown on the South Main Auto youtube channel.
Once you are backed into the corner and heater core replacement is the next step, I'd be willing to try all kinds of things even if they could damage the heater core.
If I were you I would attempt a vacuum fill of your system to rule out air pockets.
Awesome.. I am assuming the w211 and the w221 are similar.. I am going to need to do something to fix this heat issue as I live in nj and it gets cold.
the engine temp on the cluster goes up to 80 Celsius with no problem just get no heat from the vents. Just cold air. I am not sure if there is a fuse to control valve .
yet, it says that it fits w221.. I am so confused as to why I can’t get heat.. the only thing I can think is that the heater core is clogged.. ran Mercedes star and it comes up with code 9a20 and when you look up remedy it says clogged heater core
the engine temp on the cluster goes up to 80 Celsius with no problem just get no heat from the vents. Just cold air. I am not sure if there is a fuse to control valve .
the question was is this connection to the stat OK....
I don't know if its a temperature pickup - or something else that helps control the operation of the stat...
the duo valve at the back with 4 pipes and the electrical connection ... already covered (and you said changed 3 times)
BUT LETS NOT FORGET IN POST #21 YOU SAY THE COMAND IS NOT IN or PLUGGED IN THE CAR - it has the heater controls in its software ??????? what do you think is telling the heater valve to open - its not plugged in ?
there is a HVAC control module beside the fan in passenger footwell - but it all links in to the comand - as that's where u get to say what temp, what fan speed and where the air goes round the car ?
you have the white plastic fan (or maybe its black) between this and the Pollen filters sits the HVAC module (its typical ECU module size) held up vertically in the small gap by two screws and then half a million multiplugs connect to it - BUT I WOULD CONNECT THE COMAND AND SEE IF THE HEAT TURNS UP - before fiddling in the dark
First, I would plug in Command and test to confirm that is not the culprit. I have a 2007 S550 also but haven’t had to troubleshoot a “no heat” situation.
With warm upper and lower hoses at temp, coolant is circulating so it seems like there is proper flow through the system except in the heater core. I recently replaced my heater control valve because it was leaking. It is a plastic part and the old one had two connections broken off and was literally crumbling in my hands as I was removing it. I spent a lot of time fishing small pieces of corroded plastic out of the hoses that it connects. I would guess that some of those pieces travelled or lodged in the hose or heater core and are blocking coolant flow through the heater core. So as some have suggested, I would try blowing out the hoses leading to the heater core and see if that resolves the issue.
I am sure you mention this but I checked the hose coming off the back of the engine that goes to the circulation pump. The hose is cold and doesn’t seem to be pulling any coolant with the circulation pump which is connected to the change over valve. My question is does this have a fuse? This pump seems like hell to get to fyi .. below is a picture of the part and the part #
QUOTE=BOTUS;8899342]you have the white plastic fan (or maybe its black) between this and the Pollen filters sits the HVAC module (its typical ECU module size) held up vertically in the small gap by two screws and then half a million multiplugs connect to it - BUT I WOULD CONNECT THE COMAND AND SEE IF THE HEAT TURNS UP - before fiddling in the dark[/QUOTE]
the electric pump - is to circulate coolant when the engine is turned off (REST - residual heat) it circulates the engine coolant via the electric pump to provide about 30 min interior heating when switched off, but outside cold climates no one has ever touched the button and 12 years in they are mostly seized up )
I suspect without the comand in circuit and operational - you'll never open the heater valve - so it will remain cold
info on fuses in the excel file (seems on two for the heater)
2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, and 2017 Mustang GT, and just got a 2023 300C
I am convinced BOTUS is on to something here. If COMMAND still thinks you don't want heat, I'd bet a donut you will freeze this Winter. If it was me, I would plug COMMAND back in to test it.
the electric pump - is to circulate coolant when the engine is turned off (REST - residual heat) it circulates the engine coolant via the electric pump to provide about 30 min interior heating when switched off, but outside cold climates no one has ever touched the button and 12 years in they are mostly seized up )
I suspect without the comand in circuit and operational - you'll never open the heater valve - so it will remain cold
info on fuses in the excel file (seems on two for the heater)
So I guess BOTUS is saying plug the bloody command in . And that the small coolant pump is usually bad by this time in its life so it may not work either. That sucks..Does command ontrol that too? proly so ...How expensive is that part?
I have rear AC - and there is a silly pump for the rear seat REST feature and two heater solenoid valves - it sits in the gap behind the front wheel inside the bottom of the front arch liner (on my RHD its the drivers side)
these go wrong - and cost $500 were the pintel valves wear and the heat goes where isn't not supposed too - you can buy kits 'to rebuild' for $25 - but I figured everything would be worn out, I'd need gaskets you don't get in repair kits and the pump will be seized... so I got a secondhand unit from a later lower mileage car... and with a spare to play, was brave enough to pull it apart
mine put full heat on one side of the car at the back regardless of user set point - and I mean SUPER HOT - seen people with issue unaddressed, melt the plastic vents and trim and damage the leather !!! I expected getting the valve to be a nightmare - but its really simple, three hoses (so need a lot of clamps) are so long once you take it off the bracket you can sit beside the car and reach everything really easily
when I refitted the replacement - put 1 litre back in the coolant header tank and that was it as far as aggro getting the air out - after a drive I tested for the first time in my life on any car the silly REST button - don't think its right, it makes strange noises seeming to run or try to run, in strange intermittent cycles (its seems to do 20 second take a break do 20 seconds sound more like a bleed function on some industrial system). Four or so years down the line never once pressed the front one or tried the stupid feature in the back again
When stripping down the old part loads of tiny screws all rusty as hell and corrosion all over the valve bodge - once clean took apart the solenoid valves - NO gaskets just pathetic o rings you'd never believe could hold water - the seats for the pintel valves I guess you smash out to replace - I gave up as didn't see them wanting to shift and the electric motor as expected is a mess and I suspect I'll just get a water leak you'll never cure if I pull that bit apart - so its in the garage waiting for the next failure
its the very same part the w220 used - its not the cheaper readily available bit - but the repair kits while nasty and no idea if any good (that also change the design slightly) all seem to be the same
silly valve (don't remember the bottom being plastic ?)
repair kit rubbish - Heater Control Valve Repair Kit Fit for Mercedes Benz W210 W220 W221 W124
oh didn't know I had this blurry pic of the AC control module
Thank you for the very detailed post. My 07 doesn’t have the controls for the rear ac/heat just two vents coming off the center console. The part you posted I had on my w210 and rebuilt it. Was that bad and I watched a YouTube video on how to do it. What I did notice is that the hose coming from my engine which goes into the auxiliary pump didn’t have hot coolant running through it. Also the auxiliary pump according to the description is what pumps heat into the cabin. My pump is dead.. doesn’t make a noise at all while the car is on or off and the button rest is pressed. I ordered it as it’s $150 for the part. I will see if I have that part in the front wheel well as well even though like I said I don’t have the rear ac option. Lastly the climate control module seems cheap enough to buy online if need be.
12-28-2023, 11:13 AM
