Rest button doesn't work
 

Hi, on my European CL I have the REST button in the A/C module but it seems that it doesn't work. I've read the owner's manual and followed the steps and also when the engine is hot nothing to do.
Maybe the problem could be in the Push & Start Button, because the manual only explains the procedure with the key in position 2 (if I'm right)...but I tried a lot of times without success.

Do you have this feature on yours? Someone with Push & Start button which steps follow?

Thanks in advance.

The Rest button? Just want to confirm but you mean for the residual heating/cooling? In which it pulls in engine heat to heat the cabin while you lock your vehicle for up to 30 minutes or keep the fan blowing after the A/C turned off during a summer day to keep the cabin cool for up to 30 minutes while you lock the vehicle?

Yep...that one.

I've used mine w/ the key in position 1...that has worked, in my case. Does the button light up?

I have the same issue on my CL550. I haven’t investigated the cause yet.

My starter battery is a bit weak, and my consumer battery was nearly dead when I bought the car. I replaced the consumer battery when I bought the car. Maybe there’s some stored code about a weak battery preventing the REST feature from working.

No.. :(

I replaced both too...some months ago. But no faulty codes in memory... :(

Sorry to hear that. Which type of battery did you replace it with? AGM right? As for the second battery replaced, was it the auxiliary battery?

Yes, the rear one is an AGM (VARTA), the front one is for the starter, a normal one (35Ah, Mercedes branded).

What does the rear battery do? For future reference, if my battery is dead and I can't start it, jump the front one?

Yes...the front one is for the starter, the rear one is the auxiliary for all services.

Hmmm I see thanks for your confirmation, I wonder if there are any fuses that controls the rest feature? Other than that, through scanning, I wonder if any codes are stored?

Agree but I seen batteries that are perfectly capable in starting the car but it is weak enough to not have the power to enable certain features for example auto start-stop on newer MBs.

I went to my Mercedes mechanic yesterday evening, tried with Xentry tool but no faulty codes or something related to the REST feature..boh!

What about fuses, none blown right?

What are the voltages of both your batteries when vehicle is not running and the voltages of the batteries when vehicle is running?

Voltages are ok...fuses too...I really don't know where to watch...

No problem, don't stress about it. Let's see if we can figure it out. Not sure but does the W216 rest button have a light in it? (If so does it turn on at all, try checking at night in case it is just super dim). You confirmed the vehicle does have the feature right? Through a VIN decoder (in case you are not the original owner) and that the panel isn't just changed at one point but with the extra button. If it does have the feature and you were the original owner, when did it stop working?

AFAIK all C216 cars have the REST feature. I’ll update this thread if I ever get around to having this figured out. It’s nice to have in winter.

I see, sorry I wasn't able to help you out.