[Spenco100]

Hi everyone,

I’ve got an 06 330i (manuf. in 05, can’t remember the month) with some climate control issues. I recently bought this (3rd e90 for me, 4th bmw) and the heat took about 30-45 minutes to take effect, despite fans blowing well. AC worked perfectly as expected, the cold just never hit.

I read a thermostat being stuck open was the most likely cause. So I replace thermostat (previous owner had records of replacing the water pump 5k miles ago, but not the t-stat) and flush coolant, using the oem stuff of course.

No luck. Next I read that the heater core can be full of “sand” or other junk blocking it. So I used a garden hose and unblocked and tested intake / out. Seems all good, and heat now works!! But only in the passenger side.

After some testing, heat works as expected through both the mid level and top of dash vents on the passenger side, as well as the cup holder vent. All vents on the drivers side, and the back seat vent have no heat.

When I have the cold/hot dial next to the lock button set to cold, all vents function as they should. When set to hot, the drivers side and back seat (the no heat vents) they just act as fans: no heat, but not cold either. Just like when running without the “snowflake” button on.

I’ve now read that it could be my refrigerant needs a recharge, that the e90 can be finicky and show these symptoms with ANY shift in pressure in the freon lines. I’ve also read it can be the blend door motors, or a blender’s door stuck one way or the other.

Can anyone provide me some insight on how to go about diagnosing, and discover which of these 3 issues it might be? I’m happy to diagnose but would like to avoid tearing apart the dashboard. No codes have been pulled, I have a decently advanced scanner but not ISTA.

Thanks in advance!