help a/c works great but the heater won't get hot ... what do i check??
thanks in advance ... heebee







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I'm not an expert in this area but search for W210 Duovalve (heater control water valve) and see if that sounds like your problem. There should be DIY instructions for rehabbing it that you can try before replacing the part should it be the issue.

http://www.everythingbenz.com/merced...ingbenz.com%2F

Note that the 97 E420 uses a different duovalve than the E320 and E430. You will probably need this 0018307884 part, I think...

http://www.everythingbenz.com/z/part...eater-duovalve

Some models (maybe most of the other W210 models) use part 0048302084, which has a different number of inlets or outlets

http://www.everythingbenz.com/z/part...eater-duovalve

 

a/c diagnostics/check coolant level/replace your thermostat.
post the values and errors after you run the tests.

 

Well since the OP didn't continue this thread I am going to hijack it and put it to my own use! No sense in having junk threads laying around polluting the interwebs.

I'm usually in SoCal so don't notice problems with my heater but just hit the road to northern cal for thanksgiving. Now my heater problem from long ago is showing itself. Trying to run the heat, my drivers side is blowing cold (like AC cold) but I'm getting warm air out the right side.

Running the diagnostics, I'm getting the following for the sensor values. What is really odd is that sensor number 8 is rapidly cycling. It starts out at around 50 then drops steadily (one unit a second rate) to about 34... and then it JUMPS right back up to 50/51 and starts the steady drop again.

Thanks in advance for any help in diagnosing! I've cleared the errors and will check again after some driving to see what comes back.

1 - 24 (inside temp)
2 - 22 (outside temp)
3 - 28 (left vent temp)
4 - 46 (right vent temp)
5 - 05 (evap temp)
6 - 82 (engine coolant temp)
7 - 14 (refrig pressure)
8 - 49 (refrig temp - cycling number described)

error codes:

Eb1226 (in car temp sensor)
Eb1227 (outside temp sensor)
Eb1228 (heater core temp)
Eb1223 (I think this is actually 1233, refrig temp sensor)
Eb1234 (sun sensor)
Eb1235 (emissions sensor)
Eb1422 (series connection to cluster)

 

My values seem to have a pattern similar to the ones discussed in this thread, and the advice there is that the problem is in the duovalve...
https://mbworld.org/forums/e-class-w...side-cold.html

That has been my suspicion going into this but it has been hard to find similar threads to confirm. My problem isn't exactly like the one described in that link -- that diagnosis is that one side of the duo valve is stuck ON. Seems like my issue may be more that one side is stuck OFF.

From what I can gather, it seems like the duovalve is one of the primary triggers of right/left temperature differential in HEATING mode. (I very well could be wrong though). It seems like I've seen a lot more discussion of temperature differential causes during COOLING mode (usually that only one side is cooling and the other is just blowing regular "warm" aka "not cooled" air).

In my case, I suspect that somehow on my left side, the heater and the AC are fighting with each other. I wonder if I've got some bad temp sensors as well with the rapid cycling of #8 (refrig temp). I'm guessing the cycling is caused by the AC compressor coming on and off but am not sure if the duovalve would cause something like that?

The other thing that I've had suspicions about is #5, the evaporator temperature -- most of the diagnostic values I've seen have a much higher value for this item. But that didn't seem to jump out as a problem to those discussing similar values in the other thread linked above.

I'd still very much appreciate some advice from others on this!!

 

with the Evap temp sensor is that you are reading it in Celsius 5c=41f which is about perfect meaning your are fully charged and a/c is cooling when called for.
3 and 4 convert to 82f and 114f
so the left vent is cooler but not cold. Not as warm as the right side vent.
Indicated a stuck duo valve or a shot one.
Start simple,give them the old thunk on the side with the handle of a wooden screwdriver. Not a crushing blow just a good drum like thump.
Clear the error codes(erase them in the diagnostics)
Then run the tests again and see if the values for the heater cores left and right come more into line with being the same.
They should be within a few c of each other.
If still way off as 28 and 46 as current.
Dismantle and clean and lubricate duo valve.
Diy on the benzworld.org w210 forum with pictures.

 

Once again, OhLord to the rescue! Thanks so much.

 

I guess i am the op....my wife had a stroke in mid nov have'nt had a chance to work on the vehicles.....i not sure about running the diagnostics but i did take off the top of the duo valve and it is full of water....is it fixable ?? a new one is over $200.00 .....last night it got down to the30's here in san diego

 

Help!! I took apart my duovalve and tried to fix problem with no heat on one side and now I have TOO MUCH heat! I've got heat from both side vents and cold air from center vents when the AC is (and should be) running. It seems like the center vent does change between hot and cold OK, but the side vents are stuck on heat.

Could this be a stuck flap? Or did I not repair the duovalve properly? I'm wondering if the repair of the duovalve unmasked another problem or if the duovalve now has other issues. I felt pretty good about the duovalve repair but there are a few things that I might be able to check and do differently.

My new values from the AC diagnostics are below (old values in previous message in this thread).


1 - 36 (inside temp)
2 - 44 (outside temp)
3 - 54 (left vent temp)
4 - 52 (right vent temp)
5 - 08 (evap temp)
6 - 83 (engine coolant temp)
7 - 16 (refrig pressure)
8 - 49 (refrig temp)

It seems like I do NOT have any diagnostic error codes, however. I have not driven the car too much yet since the duovalve repair so perhaps there has not yet been time for them to have been thrown. I have driven the car quite a bit between clearing them and repairing the duovalve, however.

NOTE: the duovalve on the E420 and E300 is different than on most W210 models. It seems to have an extra "level" with an extra inlet or outlet. It is like the one here, and I was trying to do the overhaul along the lines described...
http://www.peachparts.com/shopforum/...self-$250.html

My guess is that this engine is setup to recirculate water through the duovalve all the time rather than just shut it off like on most other W210's? I think the extra inlet/outlet might be for the recirculation? Looking at the valve when taken apart, it does seem to be setup that way -- the solenoids don't just open and close a valve... they seem to divert the flow one way or another. I'm not sure though.

 

One other thing to note is that I did get coolant level warning after the repair, so I'm going to go add coolant to see if that helps. (Just noticed that OhLord suggested checking coolant and thermostat in previous post.) Would coolant level and/or thermostat potentially cause constant heat out side vents?

 

Pretty sure that my issue is the stems on the poppet thingys which are broken. I did read on BW about the "rivet" fix. May try that, or may just give in and order a new duovalve for $200. I'm so excited that there is actually a fix on this and I could get instant gratification that I just may keep pressing on.

 

finally had time took apart the duovalve made my own o rings just like the diy thing said too and it's a miracle heat when i want heat and cold when i want cold >>>>>>>>>>you guys are the best ...thank you very much

 

Awesome! Glad to hear it heebee. I guess I should also share that mine is fixed as well! I did the "rivet" fix and also changed out the o-rings using a couple that were in better condition from a spare of another type. I bought washers to try that fix as well but then realized I had a better option from the other valve.

Did you run into any issues fixing yours? The rings we bought (exactly the same brand/size as specified in the DIY) seemed to be just a sliver too large. We went back to the store and found some that were a tiny bit smaller and were about to use those when I thought of the other rings from the spare.

 

i actually made my own out of the sidewall of an old bike tire........ outside diameter used an 11/16 gasket punch and i think the inside hole i used a 5/16 punch......... did'nt even have to go the store...

 

Wow, I never would have thought about that. Please don't hesitate to share those types of creative solutions around here! That's a great idea and now, counting that, I know of THREE solutions to fixing those valve o-rings. Do you think that the tire material will stand up to the prolonged water and heat exposure? I guess that is pretty tough stuff...

 

donT know how the tire pieces will last but it's working a whole lot better than it was ...