My 2005 ML500 is not blowing hot or cold air at all. It only blows out the side unit not the middle or back. Is this just a fuse or a bit more? Thanks

Heater controls are done by controlling air flow thru the system. No heater valve to block water flow.

Possibly reading codes from from system could show cause of problem.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator