[fozzydj]

Originally Posted by zigsman

Okay, here is a comprehensive DIY for replacing the heater core on an E90. Mine does not have the iDrive, so, if you do, there will be a few additional and different steps. Hopefully you can work around it. If you need a larger photo (better quality), PM or email me with the task number and photo description, I'll get it sent over as soon as I can. If you get stuck somewhere along the way or have a question, feel free to PM or email me. Good luck!!

Mike
zigsman@aol.com

Hi Zigsman, thanks for the DIY.

My systemis blowing white dust out, which requires an evap change. Am I correct in thinking there is an Evaporator and a Heater core pretty much next to each other? Im thinking for the cost of a new one I may as well swap both out while Im there...

[niksss]

Hello guys ! Is this possible without removing the R134a A/C freon ? What does change if I don't remove it ?

[zigsman]

Originally Posted by fozzydj

Hi Zigsman, thanks for the DIY.

My systemis blowing white dust out, which requires an evap change. Am I correct in thinking there is an Evaporator and a Heater core pretty much next to each other? Im thinking for the cost of a new one I may as well swap both out while Im there...

I did not change the evap out when I did the heater core, but normally both are located inside the A/C plenum. So, if you are going to be removing the plenum, it would not be a bad idea to change both...it'll save you from having to remove the dash again in the future to replace the other if you only replace one now.

[zigsman]

Originally Posted by niksss

Hello guys ! Is this possible without removing the R134a A/C freon ? What does change if I don't remove it ?

No, you cannot do the job without recovering the A/C system and disconnecting the lines. The A/C lines connect directly into the A/C plenum, which has to be removed from the vehicle.

[fozzydj]

Thanks Zig

The issue only occurs for me when the A/C is on. The heating works fine and doesn't blow any dust

[Roxxen]

Big thanks zigsman for this extremely detailed DIY

[bimmerzeit]

Wow, pretty involved DIY. Hope I never have to do this!!

[Bmwater]

Thank you immensely Zigsman.

Could a blocked heater core be the reason for no heat coming from the driver side (UK model E92 325i)? The heat is perfect from the passenger side. Also the intensity of air blowing is less in the drivers side. I have seen something on the lines of 'blend door actuators'...I called BMW parts and mentioned this and he had no clue what it was. Is there a part number or a diagram to identify this part, if this is the reason for the problem?

[zigsman]

Originally Posted by Bmwater

Thank you immensely Zigsman.

Could a blocked heater core be the reason for no heat coming from the driver side (UK model E92 325i)? The heat is perfect from the passenger side. Also the intensity of air blowing is less in the drivers side. I have seen something on the lines of 'blend door actuators'...I called BMW parts and mentioned this and he had no clue what it was. Is there a part number or a diagram to identify this part, if this is the reason for the problem?

Here is a link to the heater box (parts) for the E90:

https://www.realoem.com/bmw/enUS/sho...diagId=64_1454

In the diagram, you'll see the breakdown of the actuators (#4 & #5) that control the doors in the box. I believe there is only one blend door for the temperature, not two. That being the case, if the door were broken or the actuator were broken, the temperature would still be the same on both sides of the car, it would not be different. However, I could be wrong! Beings the AC unit is dual climate, meaning you can independently adjust the temperature on each side of the car, clearly there is a mechanism that allows for different temperatures on both sides at the same time. Without doing additional research on how the AC unit functions, I don't know exactly how the unit manages temperatures. Essentially, what I'm get at is this... It might be a blend door OR it might be a clogged heater core. It's important to test the blend doors BEFORE replacing the heater core. If you don't have the diagnostic software (ISTA, DIS, etc.) to independently test the blend doors, find someone that does. With ISTA, and several other software suites, you can independently activate blend doors to ensure they ware working properly. If you find that you have a bad blend door actuator, great! If, however, you find that all the actuators are functioning properly, then it is most likely a clogged heater core.

I had the same issue with my car that you are having with yours; it was warm on one side but cool on the other. My problem was a clogged heater core.

I hope this helps!

[tino_tino]

Is it easier to change the heater core on a right-hand-drive? Just remove lower dash and get the core out?

[GSB]

Just WOW. What an amazing DIY, but what an awful job. I hope I never have to do this!
If anyone has a heater core that has blocked and gone cold, but is NOT leaking, try a heater core flush before attempting this job...
DIY: Flushing the E9x Heater Core (Caution Required!)

[zigsman]

Originally Posted by tino_tino

Is it easier to change the heater core on a right-hand-drive? Just remove lower dash and get the core out?

That's a question I cannot answer. I have never worked on a right-hand drive.

[zigsman]

Originally Posted by GSB

Just WOW. What an amazing DIY, but what an awful job. I hope I never have to do this!
If anyone has a heater core that has blocked and gone cold, but is NOT leaking, try a heater core flush before attempting this job...
DIY: Flushing the E9x Heater Core (Caution Required!)

Thanks! It was not a fun job and I knew it was a semi-common problem and figured a DIY could be helpful for many others.

[GSB]

Absolutely. Doing a DIY with your level of detail is extremely hard work, time consuming, and often goes unappreciated. So, thank you!