[swooshed]

Hello! 2015 F34 with 35K miles owner here.

I have a super frustrating heating issue that two independent mechanics could not replicate. The heat does not get hot in the car when the temperature is set to 84F and dial is set to far red. The temperature from the center air vents measure 80F max when the engine is warmed up (~200F) but drops down to ~60F when you increase fan speed to max.

Mechanic #1 has done all prior maintenance including coolant flush. Mechanic #2 noted that the coolant color was red and believes the coolant had clogged the heater core (but wasn't 100% positive). Mechanic #2 also tested the blend door actuators on the ISTA (?) computer and everything checked out. Both mechanics suggested replacing the heater core.

Flushing the heater core was not recommended as it may leak into the cabin but replacing the heater core would cost $3K.

Some F3X owners have had similar issues with their heat and a back/reverse flush on the heater core seemed to work. Is this something that can be easily DIY? Also, any concerns with the coolant color being red? Mechanic A is reputable among the BMW community and I would not expect them to use non-compliant BMW coolant.

Thanks in advance!

[fliyer]

Hello what´s about the actuator drive for blending flap ? Works there fine?