Heating system problem. No heat
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MB S500L 2006 (W221)
Heating system problem. No heat
I have a 2006 W221 S500L (same as S550 USA)
One water hose broke in the car and almost all the water came out of the car. The water hose was repaired and water was added under negative pressure and the leaks were checked. No leaks in the cooling system. Water is 80-90 degree and heat very nice.
The car has not heated the cabin since then.
I have checked the hoses, connections, changed the ShutOff Valve, DualValve (car is with Webasto) from the right fender, Auxiliary Coolant Water Pump, checked the pipes, water runs in all the pipes, but warm water does not come out of the cabin's heat cell. All water is clear and has no oil etc. This car does not have a Heater Control Valve.
15.2C and 18.6C warm air is always coming from the left valve on the dashboard. Air conditioning removes moisture and produces cold.
Winter is coming and it might be quite cold here in Finland.
Need good tips?
Could the controller be faulty or a valve broken?
One water hose broke in the car and almost all the water came out of the car. The water hose was repaired and water was added under negative pressure and the leaks were checked. No leaks in the cooling system. Water is 80-90 degree and heat very nice.
The car has not heated the cabin since then.
I have checked the hoses, connections, changed the ShutOff Valve, DualValve (car is with Webasto) from the right fender, Auxiliary Coolant Water Pump, checked the pipes, water runs in all the pipes, but warm water does not come out of the cabin's heat cell. All water is clear and has no oil etc. This car does not have a Heater Control Valve.
15.2C and 18.6C warm air is always coming from the left valve on the dashboard. Air conditioning removes moisture and produces cold.
Winter is coming and it might be quite cold here in Finland.
Need good tips?
Could the controller be faulty or a valve broken?
Last edited by JarppaFIN; Nov 5, 2022 at 06:14 AM.
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S500
air in the system ?
you already say you did the valve near the windscreen wiper mechanism (for other's its a black plastic thing with three 1" diameter houses - these are dead cheap and dead nasty - on all other Mercs this stops working and the heating plays up) - but a very respectable indy specialist near me says he's NEVER changed one on an S class - I think he's wrong
both my S500 and someone I know with a CL500 (both 550 in usa speak) have seen our heating fade away over the last 3 winters - you have to raise the set point 3 notches over what it used to and it seems to respond sluggishly and the heat has almost vanished at times
cars with the option rear AC, has a heater valve inside the front wing, its stupid money but really easy to work on - but its normal failure mode is one rear outlet goes to melting point
the Residual heat pump, does nothing unless the keys out and you press the button no one ever did on the heater controls, its designed to flatten the battery and do nothing - as when you press it you're the first to try it in 10 years and the motor is seized
could either the rear heater valve or the front heater valve be connected up wrong and the heat isn't getting to the heat exchanger?
you already say you did the valve near the windscreen wiper mechanism (for other's its a black plastic thing with three 1" diameter houses - these are dead cheap and dead nasty - on all other Mercs this stops working and the heating plays up) - but a very respectable indy specialist near me says he's NEVER changed one on an S class - I think he's wrong
both my S500 and someone I know with a CL500 (both 550 in usa speak) have seen our heating fade away over the last 3 winters - you have to raise the set point 3 notches over what it used to and it seems to respond sluggishly and the heat has almost vanished at times
cars with the option rear AC, has a heater valve inside the front wing, its stupid money but really easy to work on - but its normal failure mode is one rear outlet goes to melting point
the Residual heat pump, does nothing unless the keys out and you press the button no one ever did on the heater controls, its designed to flatten the battery and do nothing - as when you press it you're the first to try it in 10 years and the motor is seized
could either the rear heater valve or the front heater valve be connected up wrong and the heat isn't getting to the heat exchanger?
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MB S500L 2006 (W221)
Thanks for the answer. As I said, it all started when the hose between the engine and the cabin heater broke.
The new hose is easy to install, it takes about 10 minutes.
The rear heater solenoid/pump has also been renewed.
The system is under pressure, so there should be no air.
My car doesn't have that "plastic thing". This was checked from the importer's system.
I have removed the outlet hose from the cabin cell and the water circulates really well in the cell. When I connect the hose, the water doesn't seem to circulate. I'm confused.
The new hose is easy to install, it takes about 10 minutes.
The rear heater solenoid/pump has also been renewed.
The system is under pressure, so there should be no air.
My car doesn't have that "plastic thing". This was checked from the importer's system.
I have removed the outlet hose from the cabin cell and the water circulates really well in the cell. When I connect the hose, the water doesn't seem to circulate. I'm confused.
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S500
I don't know how the heater unit behaves (like all modern things its mass of hidden flaps and control) a couple of sensible steps - at normal engine temps - what temp is the coolant in and out of front and rear heat exchangers (can you reach with a laser probe thingy - I'm guessing should be at least 90 C in and at least 80 C coming out - if both are the correct side of 70 C coolant must be going round ? - but if its plastic pipes the reading might show up on the outside a lot less????
if that suggests, the heat exchangers are getting hot - it could be blend flaps within the heater unit are operating incorrectly and the heat is not reaching you - the diagnostics of the heater system is very high - and can be upgraded with a 10 min install of a later software iteration on the module - it sits beside the blower motor in the passenger footwell with a million wires going to it
using posh diagnostics tools it could tell you a lot about what's happening - they are even a lot of end user customisable mess ups that you can play with for strange customers - a reset or at least a check of fault codes would be next, if the coolant is really getting hot and going round
Of course another biggy I forgot - the engine cooling is renowned for wearing out on Mercs - its a strange set up in one of the cooling hoses - it that's wide open then its won't be making much heat
cool site to confuse yourself on parts https://nemigaparts.com/cat_spares/e...221071/63w/83/
if that suggests, the heat exchangers are getting hot - it could be blend flaps within the heater unit are operating incorrectly and the heat is not reaching you - the diagnostics of the heater system is very high - and can be upgraded with a 10 min install of a later software iteration on the module - it sits beside the blower motor in the passenger footwell with a million wires going to it
using posh diagnostics tools it could tell you a lot about what's happening - they are even a lot of end user customisable mess ups that you can play with for strange customers - a reset or at least a check of fault codes would be next, if the coolant is really getting hot and going round
Of course another biggy I forgot - the engine cooling is renowned for wearing out on Mercs - its a strange set up in one of the cooling hoses - it that's wide open then its won't be making much heat
cool site to confuse yourself on parts https://nemigaparts.com/cat_spares/e...221071/63w/83/
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'10 CL550, '12 GL550
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MB S500L 2006 (W221)
I don't know how the heater unit behaves (like all modern things its mass of hidden flaps and control) a couple of sensible steps - at normal engine temps - what temp is the coolant in and out of front and rear heat exchangers (can you reach with a laser probe thingy - I'm guessing should be at least 90 C in and at least 80 C coming out - if both are the correct side of 70 C coolant must be going round ? - but if its plastic pipes the reading might show up on the outside a lot less????
if that suggests, the heat exchangers are getting hot - it could be blend flaps within the heater unit are operating incorrectly and the heat is not reaching you - the diagnostics of the heater system is very high - and can be upgraded with a 10 min install of a later software iteration on the module - it sits beside the blower motor in the passenger footwell with a million wires going to it
using posh diagnostics tools it could tell you a lot about what's happening - they are even a lot of end user customisable mess ups that you can play with for strange customers - a reset or at least a check of fault codes would be next, if the coolant is really getting hot and going round
Of course another biggy I forgot - the engine cooling is renowned for wearing out on Mercs - its a strange set up in one of the cooling hoses - it that's wide open then its won't be making much heat
cool site to confuse yourself on parts https://nemigaparts.com/cat_spares/e...221071/63w/83/
if that suggests, the heat exchangers are getting hot - it could be blend flaps within the heater unit are operating incorrectly and the heat is not reaching you - the diagnostics of the heater system is very high - and can be upgraded with a 10 min install of a later software iteration on the module - it sits beside the blower motor in the passenger footwell with a million wires going to it
using posh diagnostics tools it could tell you a lot about what's happening - they are even a lot of end user customisable mess ups that you can play with for strange customers - a reset or at least a check of fault codes would be next, if the coolant is really getting hot and going round
Of course another biggy I forgot - the engine cooling is renowned for wearing out on Mercs - its a strange set up in one of the cooling hoses - it that's wide open then its won't be making much heat
cool site to confuse yourself on parts https://nemigaparts.com/cat_spares/e...221071/63w/83/
I'm going to an authorized repair shop tomorrow. Let's see if they can find anything.
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S500
I miss typed in post 4, I mean to say the engine cooling thermostat plays up on most mercs,
if that far up north do u have a button on the dash to set a timer for a block heater to keep it warm at night with the engine off? otherwise (and even if you did) i don't get why it wouldn't have a change over valve
cars with block heater https://nemigaparts.com/cat_spares/e...71/63w/83/182/ part 160 you do have the black plastic change over valve that always goes wrong ???
for normal cars in warmer climates its part 170 https://nemigaparts.com/cat_spares/e...71/63w/83/181/
this is what (as far as I know) makes the heating in the front work - when it gives up u get no heat
if that far up north do u have a button on the dash to set a timer for a block heater to keep it warm at night with the engine off? otherwise (and even if you did) i don't get why it wouldn't have a change over valve
cars with block heater https://nemigaparts.com/cat_spares/e...71/63w/83/182/ part 160 you do have the black plastic change over valve that always goes wrong ???
for normal cars in warmer climates its part 170 https://nemigaparts.com/cat_spares/e...71/63w/83/181/
this is what (as far as I know) makes the heating in the front work - when it gives up u get no heat
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S500
if you have star - there is a reset procedure to get all the flaps to re-sync - must do it with the ENGINE off - which means the battery goes flat, so your need to get it some support to complete this bit successfully
might as well give it a go - is it in the OCP module - this is a right strange component up by the interior mirror, it talks to lots of the car on lots of lines of communication and is a fussy little ----er, that has to have the engine off to do some stuff
might as well give it a go - is it in the OCP module - this is a right strange component up by the interior mirror, it talks to lots of the car on lots of lines of communication and is a fussy little ----er, that has to have the engine off to do some stuff
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MB S500L 2006 (W221)
I have been looking for that valve 160/170 but can't find it in my car. This would be an easy solution if the fault was in the valve. The valve is normally under the windshield wipers, but in my car that valve is not there, at least at that point, and I can't find a connector for it.
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MB S500L 2006 (W221)
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S500
what is there near the brake servo closer to the centre of the car rather than next to the F SAM? if its a std car with the 5.5 l NA v8 I think you should have the black plastic bit - that's the heater valve
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Does not sound right. Send pix of firewall area both center and drivers side.
As Botus has said, most of us have had to replace the plastic heater control valve typically after 8-10 years. Not a hard repair. Just don't use a Chinese pattern part. Mine was replaced at about 75K miles. Same story, no heat. Just very cold air during the Winter. Not fun. Replaced the valve with an OEM replacement. Now heating perfectly.
As Botus has said, most of us have had to replace the plastic heater control valve typically after 8-10 years. Not a hard repair. Just don't use a Chinese pattern part. Mine was replaced at about 75K miles. Same story, no heat. Just very cold air during the Winter. Not fun. Replaced the valve with an OEM replacement. Now heating perfectly.
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MB S500L 2006 (W221)
SOLVED !
The solution to the problem was the right valve/solenoid next to the Webasto in the inner fender. The valve was stuck. Changing the valve was quite easy even though it is behind Webasto.
This car does NOT have a Heater Control Valve. The part can be found in the Independent Heating section. Part number A0005062864. Orginal Valve cost 558€. Bosch Valve 37.80€
Thanks to everyone for the help and advice
The solution to the problem was the right valve/solenoid next to the Webasto in the inner fender. The valve was stuck. Changing the valve was quite easy even though it is behind Webasto.
This car does NOT have a Heater Control Valve. The part can be found in the Independent Heating section. Part number A0005062864. Orginal Valve cost 558€. Bosch Valve 37.80€
Thanks to everyone for the help and advice
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S500
that valve normally makes the rear heating go strange - mine and as I read on this forum to quite a few owners - usually goes RED hot one side at the back and everything else still works exactly the same
info on the 38 dollar valve would be nice ? - they are crazy money - note this was the exact same part also used on the older w220
part 350 ?
https://nemigaparts.com/cat_spares/e...71/63w/83/183/
info on the 38 dollar valve would be nice ? - they are crazy money - note this was the exact same part also used on the older w220
part 350 ?
https://nemigaparts.com/cat_spares/e...71/63w/83/183/
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S500
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MB S500L 2006 (W221)
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S500
what a crazy way to write a parts drawing - so you have half the bits in one place section 50 and the other half of the SAME engine cooling system under section 83 and then refer to different bits of the independent heating within BOTH
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MB S500L 2006 (W221)
Yes, The best thing about this is that there is no description or drawing of the system in WIS. According to the EPC, my car has an auxiliary heating valve, but it doesn't really exist and according to the factory card, it never did. The car's heating is under HEating system, Radiator and Cooling system. The overall picture cannot be found.
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From: Iowa
2008 CL550, 2022 EQB 300, 2023 EQS 450 4Matic
I've had a somewhat cold winter in my 2008. I've had to keep the temperature on about 77 degrees to keep the car warm. Yesterday I tested what is coming out of the vents...both outer vents were at 100 degrees on max heat with the car at operating temperature, and the middle vents at 65 degrees, with outside temperature 30 degrees. Anyone know what to make of this? Heater control valve problem?
