W210 Climate Control Quirk - PeachParts Mercedes-Benz Forum

shertex · #1 11-22-2013, 10:49 AM

As mentioned in another thread, the aux water pump on my 98 E300D is offline (leads actually cut, presumably because the pump had failed). I think I'm happy to live without the AWP. However, I've noticed something else. In cold weather, with CCU set to auto and to a nice warm temp, the vents are blowing cold air before the heater core has warmed up. It shouldn't be doing this....part of the way the ACC works is that there shouldn't be air at the vents until there's warm air to be had.

Is this likely related to my AWP being offline? Or is it an unrelated malfunction?

Is a climate control reset likely to help? If so, how do I do that.

Not a big deal....if I need to wait a few minutes to turn on ACC, that's fine.

shertex · #2 11-23-2013, 08:17 AM

Anyone?

jay_bob · #3 11-23-2013, 08:19 AM

search (either here or on the web) W210 climate fault code

There are 3 diagnostics
- the REST button status screens
- The fault code (really pulls the Bxxx OBD fault codes for the climate)
- the function test

There are several good writeups about this to be found

shertex · #4 11-23-2013, 08:24 AM

Quote:

Originally Posted by jay_bob

search (either here or on the web) W210 climate fault code

There are 3 diagnostics
- the REST button status screens
- The fault code (really pulls the Bxxx OBD fault codes for the climate)
- the function test

There are several good writeups about this to be found

Thanks....I will see what fault codes I have.

shertex · #5 11-23-2013, 08:37 AM

When I pulled the codes, there were three:

B1231 ECT sensor (B11/4)

B1234 Sun sensor (B32)

B1416 Coolant circulation pump (M13)

I cleared the codes and the only one that remains is B1416.

So am I to conclude that the absence of the pump in and of itself is responsible for the air blowing before it warms up?

jay_bob · #6 11-23-2013, 09:19 AM

I would keep a watch on the codes and see if they return.

Sun sensor is relatively easy to change (the little pyramid in the center front of the dash).

Not sure which sensor is the ECT (Engine Coolant Temperature) sensor. Maybe poking around in EPC might help you find it. Unfortunately they don't list the diagram component ID numbers (the "B11/4") in EPC. By the way the component ID numbers do have a pattern. It's all laid out in a DIN standard. "B" is a sensor, "M" is a motor, etc. 11 means the 11th sensor on the drawing, the /4 means the 4th device within that sensor.

I would try disassembling the pump and see if you can figure out what's wrong with it. I know those are rather expensive new so maybe try eBay or the yard first if you can't save yours.

The ECT sensor may be what your problem is with the cold air blast, the 124s had 2 discrete switch sensors for the ACC. The 210 changed to an analog sensor. They probably do the same 2 things with that one sensor - hold off on the heat before the engine has to warm up, and cut back on the a/c if the engine starts to overheat.

When you start the car next, put the panel in diagnostic mode (hold down REST for 5 seconds) then look at parameter 6. That is ECT value in Degrees F. See if you get a plausible number compared to the cluster gauge.

shertex · #7 11-23-2013, 09:23 AM

I don't know whether it was clearing those two codes that did the trick, but now I'm no longer getting the cold air at start-up.

I can get a used AWP for $50 on eBay....a new one for $160 or so. I think I'm happy to live without, especially since I have another car.

shertex · #8 11-23-2013, 09:30 AM

When a code is thrown for the first time, does it simply appear? Or do I have to go through the diagnostic procedure to see it?

shertex · #9 11-23-2013, 10:07 AM

I guess it makes sense that clearing the ECT code could account for things returning to normal.

jay_bob · #10 11-23-2013, 12:45 PM

Codes will not appear until you do the "view codes" procedure. Only exception to that is something that inhibits the compressor, that causes the EC light to come on and you can't turn it off.

Not having the AWP will cause the system to have trouble maintaining an even temperature especially in stop and go traffic. If you mostly drive highway then you will probably be ok. But if you drive in the city you will have issues with getting hot and cold blasts as the system tries to cope with the lack of water flow at idle.

I would look at trying to fix it. First thing I would do is try to pull the pump and hook it direct to the battery and see what happens. You should see the impeller turning through the ports. You can also try to put a short piece of hose on the center port, and see if it pumps water from a tray. Note that the pump has no lift capability to speak of, so arrange your test so that it is moving the water horizontally.

When the climate control is working correctly you can leave it on your desired temperature (I like 68 myself) and you never even notice it working. Well maybe except when it is 95 degrees out, and you've been parked in the sun, then it is blasting for all it's got until the car cools down.

shertex · #11 11-23-2013, 02:07 PM

It's been fine in the 30's....we'll see how it does when it gets really cold. I'll live without the AWP this winter then see what I think.