Hello all
I have 2004 300m, the heat will not work. I checked all fuses. Changed thermostat, new radiator, changed blend door actuator. Even changed control panel. The air will only come out of the forward facing vents. A/c comes out cold. Just no heat...someone please help.

 

warm engine up then deel bot heater core lines are they hot where you cant hold them or are they cool?

 

Yes..i also checked that..they are hot

 

when you took off the blend air door motor could you move the door manually? If thats good then last thing you have would be a BCM or fuse box issue

 

RECALIBRATING YOUR AC:
1. Start the engine but do not move the vehicle.
2. Set the Temp control to 75 degrees.
3. Press and hold the Floor, Mix (vent/defrost) and Defrost buttons at the same time. The floor is a bottom button and the others are upper.
4. The control head will begin to blink and enter a diagnostic mode.
5. Release the Floor, Mix and Defrost buttons.
Once the unit has gone through its diagnostics it will either return to its normal mode (with all air doors calibrated) or it will return one or more of 16 different error codes between 23 and 51. The ATC control can only show one diagnostic trouble code at a time. Under certain circumstances, more than one diagnostic trouble code could be in the memory. To scroll through any additional diagnostic trouble codes, press the Panel Mode button on the ATC control. Any other button or turning of a **** will end the diagnostic test without showing the rest of the trouble codes.
This will calibrate and set up the blend door.

 

I have done this a few times...code 24 comes up..but i have changed this part i believe....please let me know if it needs to be changed again...but for sure says 24