W210 CCU "EC" light on all the time

[ROLLGUY]

My friends E300 has the EC light on all the time on the climate control. No mater what buttons are pushed, the light remains on. Could it be a mechanical problem with the actual button? Or could it be something amiss electronically? I have another one available in a parts car if needed. I would also like to know how to remove it, should the need arise. Thanks in advance, Rich

[tjts1]

Check for codes. It'll do this when the AC clutch coil is toast, among other things.

[ROLLGUY]

Originally Posted by tjts1

Check for codes. It'll do this when the AC clutch coil is toast, among other things.

The CEL is not lit, but maybe there is a code in there anyway. I will check, Thanks.

[tjts1]

Originally Posted by ROLLGUY

The CEL is not lit, but maybe there is a code in there anyway. I will check, Thanks.

Sorry, I should've been more clear. The W210 CCU has a hidden menu that can show you climate control specific fault codes. It makes diagnostics super easy.


DCT table:

B1226 - In-car temperature sensor (B10/4)
B1227 - Outside temperature indicator temperature sensor (B14)
B1228 - Heater core temperature (B10/1)
B1229 - Heater core temperature (B10/1)
B1230 - Evaporator temperature sensor (B10/6)
B1231 - ECT sensor (B11/4)
B1232 - Refrigerant pressure sensor (B12)
B1233 - Refrigerant temperature sensor (B12/1)
B1234 - Sun sensor (B32)
B1235 - Emissions sensor (B31)
B1241 - Refrigerant fill
B1416 - Coolant circulation pump (M13)
B1417 - Duovalve (Y21y1), left
B1418 - Duovalve (Y21y2), right
B1419 - Electromagnetic clutch (A9k1)
B1420 - Idle speed increase
B1421 - Pulse module (N65)
B1422 - Series interface (K1) connection to instrument cluster (A1)
B1423 - Switchover valve block (Y11)
B1424 - Activated charcoal filter actuator (A32m2) open
B1425 - Activated charcoal filter actuator (A32m2) closed
B1432 - Non-USA DTC
B1459 - Series interface (K2) connection to instrument cluster (A1)
B1462 - Wide open throttle (WOT) position signal: diesel engines

[ROLLGUY]

tjts1 THANKS! That is very useful information. I printed it out for reference. That is what I like about this forum, help is always only a forum post away!

[sixto]

Removal is the same as the OE radio - slip puller tools into the horizontal slots at the bottom of each AUTO button and extract. Lift the latch to release the electrical connectors.

These things don't go bad like earlier PBUs.

Sixto
83 300SD
98 E320

[ROLLGUY]

Originally Posted by sixto

Removal is the same as the OE radio - slip puller tools into the horizontal slots at the bottom of each AUTO button and extract. Lift the latch to release the electrical connectors.

These things don't go bad like earlier PBUs.

Sixto
83 300SD
98 E320

Thanks, I kinda figured that, but was not absolutely sure. I am hoping there will be a climate control trouble code that will lead me to the necessary repair.

[sixto]

EC light usually means low refrigerant but the built-in diagnostics will guide you to certainty.

Sixto
83 300SD
98 E320 wagon

[Zulfiqar]

the EC light on mine lit up when the compressor clutch coil toasted itself. The CCU checks its resistance to ground. If open it will pop its code and make the compressor inoperable.

Good thing now is that you can buy that coil for cheap. You can also install a coil from some other car without the thermal fuse, the only risk you will face is the belt shredding if the compressor locks up internally.

If its an M112 car - its very easy to R&R, if its a 606 engine car - its a bit more cramped.

[jay_bob]

My W210's compressor seized, the system with the thermal fuse worked as designed. I would not want to risk bypassing this. If the compressor seizes and it does not disengage itself you will shred the belt and worse.

606 turbo compressor not all that hard to remove, you do have to get the intercooler pipe out of the way first. Once you do that the compressor drops out through the opening in the LCA.

Also remember that these are Bxxx or Body OBD codes. On the 1st gen W210 (which all the US Diesels are) only Pxxx or Power train codes come out of the OBDII port. There is a bridge between the Body and Power Train CAN buses through the ignition switch but the B codes do not pass through to the P bus.

[Zulfiqar]

Originally Posted by jay_bob

My W210's compressor seized, the system with the thermal fuse worked as designed. I would not want to risk bypassing this. If the compressor seizes and it does not disengage itself you will shred the belt and worse.

606 turbo compressor not all that hard to remove, you do have to get the intercooler pipe out of the way first. Once you do that the compressor drops out through the opening in the LCA.

Also remember that these are Bxxx or Body OBD codes. On the 1st gen W210 (which all the US Diesels are) only Pxxx or Power train codes come out of the OBDII port. There is a bridge between the Body and Power Train CAN buses through the ignition switch but the B codes do not pass through to the P bus.

yes good point - the body codes only are read through the round 38 pin port in the engine room fusebox on the W210 models.