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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #1
Hey people, i was wondering if anyone could help me out, i have a 2001 S430, the problem i'm having is with my heat, the car takes awhile to heat up and when it does its not really warm and i notice when i come to a stop the car starts to blow cooler air. I know i have no rad leaks and i just topped up the coolant level. Does anyone else experiencing this problem and what do you suggest i do....plz help.
 

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W221 & Audio Moderator
2013 S550
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10,978 Posts
Possibly a bad duovalve. Please see the writeups in the W220 S-Class Encyclopedia sticky at the top of the forum.
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #3
Thx, but i'm sorry can you be more specific of where exactly i look cuz i can't find anything about duovalve...thx
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #4
Sorry my bad i found it, looks like i have to replace my Duovalve...thx again
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
Be sure to check the pipes to and from the duo valve as they should all be hot and if not then change the valve. Also check the live feed to the valve as this may simply be a blown fuse.
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #6
Thx Eric but i'm not too familiar with finding all the fuses and where exactly they are. The blower works fine and gives off some heat when driving but like i said earlier it starts to cool down when i come to stop. Is there a chance that i can preserve the old duo valve or do i need to just get a new one and also where can i find one for the prices that are displayed in the instructional thread, guys said they got one for around $60 but according to the parts sites i went to they cost around $400...ouch What is the exact name of the part is it ACC dual valve?
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
You should complete your profile as we do not know which country you are in let alone which part of that country. Just a thought, check your AC filters as it may be they are partially blocked and not enough air can get through.
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #8
Sorry i will fill that out asap, i live in Canada. Where are the AC filters located?
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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Registered
2002 s500, 2004 S500 fourmatic
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267 Posts
This does seem to be a common problem! I've got the same thing going on as well, however I don't think its the duovalve, as you are getting some heat when you move. Try using the REST function. If it starts blowing warm when the motor is off, and then progressively gets colder until its blowing cold outside air, I would tend to say its more likely to be the auxiliary coolant pump.

Where in Canada are ya?

Ron
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #11
Ok i'll have to try that, i'm in Windsor, Ontario
 

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2002 s500, 2004 S500 fourmatic
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267 Posts
I'm in Kitchener.

I actually replaced the pump yesterday afternoon. Didn't seem to be working on the way home, but this morning it is. Yippee. But I get "low coolant" message on the display this morning! Booooooo.

Seems I forgot to tighten the rad pressure cap, at least thats what I'm hoping because I don't see any coolant pooling anywhere when I checked this morning. I'll have to go out and check the pressure, it may just all be in the lower reservoir and couldn't resiphon itself back into the main.

The job is not very complex. Took about 1-1/2 hrs. to swap new for old. Don't have a garage so I didn't want to do it on the driveway with the weather we are having.

One thing I did do was with all the hoses attached and just the old pump in my hand, I turned on the "REST" function to see if the motor spun. It's delayed in the circuit, but the old one would lock up quick when the new one spun nice. I'll bet its just brushes worn down. I'll bust it a part later to confirm. Interesting pump design in that there is no direct connection to the impellor, relies on magnetics to spin. Cool

Cheers for now

Ron
 

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2001 mercedes S430, 2010 mercedes E550 4matic
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340 Posts
Discussion Starter #13
Hey Ron,
Not sure if you looked at the Diy instructions in the sticky forum, but does the part for our cars look like that valve or is it alittle different and where did you get your new valve and how much did you pay for it? I looked for it online and cant seem to find it, what is the exact name of this part? can you text me 519-984-1534 not sure if we're allowed to put numbers here.
 
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