Hi. I am new to the forum and need help please. I have a 2002 ml320 with a heater issue. I cannot get any better than cool air when I set the heater to a high temperature. I have checked that the actuator behind the glove box moves and it seems fine. The heater pipes seem hot and the coolant level is good. I have checked fuses and all is fine. Im not sure where to go from here. Any help is greatly appreciated. Im not bad mechanically but do need detail please. Many thanks.
I have read in several places about the duo valve and will have to check mine had one. I have removed the glove box and can see the actuator moving with the temp dial so I'm guessing thats ok. How do I check a duo valve or service it please?
shane ml320
New Member
- Joined
- Oct 17, 2013
- Messages
- 10
- Car
- ml320 2000 plate
Hi guys new to this just wondering how to make a new post i have tried everything and can only seem to reply to new posts any help would be grateful thanks! Sorry if i have interupted on anyones post 
shane ml320
New Member
- Joined
- Oct 17, 2013
- Messages
- 10
- Car
- ml320 2000 plate
Sorry to interrupt i am really stuck on how to make a new post all i seem to be able to do is reply on peoples posts 
any help would be appreciated
any help would be appreciated
Sorry to interrupt i am really stuck on how to make a new post all i seem to be able to do is reply on peoples posts
If your question is about electronics then go here… Electronics - MBClub UK - Bringing together Mercedes Enthusiasts …near the top of the page you will see a button like this…
Click it and type your question.
Dec
Jane270ML
Active Member
Does this help... http://www.mbclub.co.uk/forums/howto/26888-howto-clean-duovalve-w210.html .. found it in the HOW TO section
Is that a coolant recirculation pump in your pictire, see… Fuse keeps blowing, ML320 - Benzworld.org - Mercedes-Benz Discussion Forum
Also… Auxillary coolant recirculation pump question - Benzworld.org - Mercedes-Benz Discussion Forum
Your picture is a bit too close up, hard to see what you got there.
Dec
Also… Auxillary coolant recirculation pump question - Benzworld.org - Mercedes-Benz Discussion Forum
Your picture is a bit too close up, hard to see what you got there.
Dec
I don’t know your car but yes I THINK? if that pump doesn’t run then no heat in cabin….fuse?
With the engine running…careful.. put your hand on the pump, you should feel it “throb“ if I is working.
Did you see the DIY in the .pdf in post number 31 here…DIY thread collection - Page 4 - Benzworld.org - Mercedes-Benz Discussion Forum
Dec
With the engine running…careful.. put your hand on the pump, you should feel it “throb“ if I is working.
Did you see the DIY in the .pdf in post number 31 here…DIY thread collection - Page 4 - Benzworld.org - Mercedes-Benz Discussion Forum
Dec
I have just warmed the engine up to operating temp. I can feel a slight buzz from the pump when I put my hand on it and the hose going into the bottom is quite hot andthe ones coming out of the top are just warm. When I turned the engine off the pump buzzing stopped as well. Am I perhaps mistaking the pump buzz as vibration from the engine? Is there anyway to check the pump ?
The hose going into the bottom of the pump and the hose coming out of the pump should both be equally hot if water is circulating through the pump.
This is an American manual but see page 110 residual heat switch 7 here… http://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/ownersmanual/2002_ml.pdf
And
Page 117 residual engine heat utilization, get engine up to 80c and see if the pump will run with the key in ignition 1 position as described in page 117.
Dec
thank you, I have just tried that and the pump doesnt buzz at all, the engine temp was just over 80 degrees, i turned the key to both position 1 and 2, and although the pipes above and below the pump were hot, i could not feel the pump buzzing....
In the left side of the picture below is my recirculating pump, if I touch the end nearest the bottom, where the wires are, I can feel the vibrations of the motor, at the other end I can feel the pulse of the coolant as it goes through the pump so if you don’t get any vibrations then the pump is dead or not getting any power.
Unplug the pump and check for 12v.
Check fuses also.
Dec
Unplug the pump and check for 12v.
Check fuses also.
Dec
thank you, on mine it is the same pump but vertical, I will check it tomorrow with my vltmeter, but im sure theres no vibration as you describe, I have found another on the internet should i need a replacement, i did check the fuses but on mine it must have several functions as there isnt one on the list purely for the pump, does yours have a separate fuse?
