Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, welcome to Just Answer. My name is***** don't see how this could be a temperature control module problem. The Y34 vacuum switchover valve is controlled by the pushbutton switch. This has to be either a defective pushbutton switch or Y34 valve or the plugs on the pushbutton switch are reversed. This problem is too complicated to try and sort out in this format. I will need to talk to you on the phone for this problem. I've sent you an additional service agreement if you would like a phone call. If you accept the agreement I can call you in the morning.
Looks like the additional service tab is not working. I'll check with customer service and reply back.