V Klasse Defrost Air Distribution Flap Issue

Regarding your V Klasse's HVAC unit issues, it sounds like you've done your homework. A faulty defrost air distribution flap motor or its associated wiring is a common problem. Low heater core output often accompanies it, as the air isn't being directed properly. Have you checked the basics first, like visually inspecting the wiring harness and plug that goes to the flap motor? Can you hear the motor trying to actuate when you change the climate control settings? If you've got access to a multimeter, probing the connector for voltage when you select defrost would be smart before tearing into the dashboard panel. It could save time and money. Do you have a scan tool that can provide live data from the HVAC unit? That would allow you to see the commanded position of the flap versus the actual position, which could pinpoint a mechanical issue too.

I have visually inspected the wiring harness and plug, but I did not detect any obvious damage. I am uncertain if I can hear the flap motor. If the motor is trying to actuate, where exactly can I pinpoint its location to listen attentively? Also, I am not equipped with a scan tool capable of providing live data. Where is the flap actuator located?

Okay, if you can't hear the motor, and you lack the capability to read live data from the HVAC unit, it's becoming progressively more difficult to diagnose without further disassembly. The defrost flap actuator is typically buried within the dashboard panel, often behind the center console or near the heater core. Accessing it usually involves removing a considerable portion of the dashboard, which can be quite involved. Without proper diagnostic tools, you're essentially troubleshooting blind. Given the potential for further complications and the need for specialized equipment, I'd strongly advise taking it to a workshop. They can accurately diagnose the problem, confirm whether it's indeed the actuator or something else, and perform the necessary repairs. The 95€ estimate seems reasonable, especially if it includes labor and parts.

I appreciate your guidance. Based on your advice, I took the vehicle to a trusted workshop. You correctly diagnosed the issue, and upon further inspection, the mechanics confirmed that the cable was defective. Replacing the faulty cable and plug connection resolved the diminished heating output. Thank you for helping.