I have a '99 ML 320. Since this summer, I have had A/C and heater problems. A/C does not blow cold and the heater does not blow hot air. From reading some of the other posts in this forum, it seems to me that the problem might be with the actuator. I took the ML into a local repair shop that specializes in MBs. They are telling me they need to replace the heater box, which should solve the issue with the heater but they wouldn't give me a solid answer on whether this would fix the A/C issue as well. Would a faulty/broken heater box cause the A/C issues as well?? Thanks for all comments and assistance.

 

very very doubtful that its the heaterbox, take it to a MB dealer and see what they say. could be the pushbutton unit itself. check the basics first.