03 Z4 2.5L, 170k miles With temp knob at max heat car blows lukewarm warm air out footwell and cool air out upper vents. Fan working normal. Recently replaced water pump, expansion tank and thermostat. Car was bled by mechanic and I ensured it was topped off. Both heater hoses are firm and hot when car is at temp. No abnormal gauge readings. I'm leaning to something electrical or a jammed mixing valve. Maybe a temp sensor?
Sounds like you might have a plugged heater core or the mixing flap in the dash is not working properly. Since you have had all the coolant work done I lean more toward a plugged heater core. My suggestion is to take off both the heater core lines and run some cleaner and compressed air through it to clean it out. Rebleed the system and test to see if the heat improves.
Followed your suggestion and heat has improved. Not at 100% but maybe my technique. Didn't see much crud come out, but I'll take it. Thanks
Yes It does take a few attempts to get it 100% again may wanna run some high flow water through it as well to help try to dislodge whats causing it.
Symptoms suggest that not all the air has been bled from the cooling circuits; classic Z-Series malady
