MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (5 sections)
The Problem
On several Mercedes-Benz models produced from 1996 to 2003, the climate control (A/C) or heater buttons may stop working or responding. For example, when you press the buttons to change the temperature up or down, the temperature doesn’t change. Press the fan buttons, but the speed of the blower fan doesn’t work. If you pay close attention, you may notice that the button doesn’t spring back. This is caused by broken plastic on the back of the buttons.
The Solution
This may often be misdiagnosed as a bad climate control unit, and some mechanics will replace the whole unit, but that is not necessary. It is possible to repair the broken buttons, and there is no need to buy a completely new unit.
To replace yours, you can buy a used Mercedes Climate Control Unit (eBay link) online. These units don’t require programming.
or
Use a third-party service that specializes in fixing Mercedes-Benz climate control units.
Step 1
If you have the right tools, you will need to remove the climate control unit, which takes less than five minutes. Â You will need: Mercedes-Benz Radio Climate Control Removal Tool
Step 2:
Next, order a repair service online. We use Module Medics, a US based mail in repair service for Mercedes electronic modules.
Step 3:
Mail your unit to the provided address. Please wait for it to be fixed and returned to you. Typically this takes about 5 to 7 days if you live in the US.
Step 4:Â
Install the climate control unit. Connect the wire harness on the back and press it in until you hear it lock in place. You should hear a click when the climate control unit is fully inserted. If the LCD is too dim, change the small light bulb on the unit before you reinstall it.
This method has the benefit of not requiring the climate control unit to be reprogrammed. Repairing the unit is much cheaper than replacing it.
Applicable Models
The climate control unit is found on the following Mercedes-Benz models.
- 1998-2003 CLK-Class W208: CLK320 CLK55 AMG CLK430
- 1996-2000 C-Class W202: C220 C250 C280 C36 C230
- 1998-2002 S-Class R129: SL500 SL600
- 1996-2003 E-Class W210: E320 E430 E55
Related Part Numbers
- 140 830 26 85
- 1408302685
Check It Is the Unit Before You Post It
Everything above assumes the climate control unit is the thing that has failed, and on these cars it usually is. It is still worth confirming before you box one up and mail it across the country, because a unit that has lost its power supply or its connection to the car behaves exactly like one with dead buttons from the driver’s seat.
The climate control unit sits on the car’s network and reports faults like any other module, which a basic OBD2 reader will not show you because it only talks to the engine. A scanner that reads the comfort control units, such as the YOUCANIC UCAN-II Pro, will tell you whether the unit is talking to the car at all. If it is not, the problem may be upstream of the unit and posting it away will not fix anything.
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
Thank you for this discussion! The EC button on the A/C control panel is apparently stuck (non-functioning). I am in the process of resolving this issue!