How to change a heater change over valve in a 221,216 and 230


Always remembered RIP
Mar 14, 2005
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Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Changing the heater shutoff valve on a 221/216 and also a 230


Heating illogical or poor, cooling illogical or poor, one side hot when it should be cold and the other way round. Maybe ok one day but not the next.

Changing this valve is quite easy on the 221/216 but you need small hands to do it on the 230. In all cases it is situated in front of the windscreen under the plastic cover.

It is a cheap device at £35 (I had it stock since 2009 but never used it) and it is the same part number for all 3 models.

Part number A230 830 00 84

First use some tape to mark where the wiper blades are resting on the screen, some cars have a white marker line, but not all for this.

The first job it to remover the wiper arms, and they can be hard to remove as they corrode onto the shafts. I use a small puller to avoid damaging the wiper arms. As you tighten the puller bolt they come off with quite a crack.

The next job is to remove the plastic water cover below the screen, this just prises out of a groove below the screen. In the case of the 221/216, unhook the rubbers on B pillars where they slot into the plastic cover. On no account use any metal blade to lift this cover out of the fixing slot or you will crack the screen, I use a nylon cooking spatula starting at one end, its hard to get it started but it does come out. Next unclip the clip on the front of the cover and it’s off.
Here the plastic cover is upside down so you can see the part that clips into the bottom of the screen

I did not drain off any water and only ½ a cup full of antifreeze mixture came out.

The clips used on the water pipes can be a mixture, on my 216 it had 3 Clix fittings and one odd one that works in the same way, but a much heavier duty for the water in pipe. Clix tongs can be bought on Ebay circa £10 and you cannot do it without, I also needed a tool with a flexible shaft as access was limited and the clamp ears can be anywhere round the pipe, Just open the Clix clamp and slide it back just over an inch along the pipe, this will allow the pipe to be pulled off. Do all 4 and then release the electrical connector and its out. It might look easier to remove the hoses from the heater box and then change the pipes over to the new valve, but heater boxes are very expensive to buy and fit, if you damaged a pipe you could be in trouble.

Refit the new one dry as it is plastic, once done start up and check for leaks, the engine will need to get above 80c to check this properly.

Another job well worth doing while the water cover is off, that is to clean out the drainpipes and the ends on the water cover. My nearside drainpipe was blocked solid
A job well worth doing.

Mercedes-Benz Servicing, repairs, engine and diagnostics
Wayne Gates - Mercedes-Benz, Unit F3, Phoenix Industrial Estate, Rosslyn Crescent, Harrow, Middlesex, HA1 2SP
Tel: 020 8863 9233
Established for 20 years all vehicles washed and vacuumed.
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