Can anyone tell me why my 92 300D. Heater will only blow very hot air out the window vents while driving.
the fan control, climate control is not working in any functions, just blows hot air from window vents while driving. prior to that it worked intermitenly at some times blowing hot air out the window vents & cold air out the floor vents at the same time when trying to use the A/C. I don't know what needs replacing.
Thanks in advance for tech help

Sounds like you've lost power to the AC controls so start with the fuses. Some MBs of this vintage have a separate 30 amp strip fuse for the blower in a separate case attached to the left strut tower.

Sixto
83 300SD

Ill check the fuse, Thanks

And check fuse 7 in the main box. That is the control power for the climate control.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech