[F32Fleet]

While not specific to this issue a failing heater control valve can cause low/no heat condition for the entire system.

This valve is present on vehicles with automatic climate control and is found on the driver side of the engine bay at the coolant line leading to the heat exchanger.

The valve is either open or closed and should throw a code if failed. One manual way to test it is to feel the difference in temperature on a fully warmed running engine with the heat on max temp.. If the hose AFTER the valve isn't hot then it might be failing.

[F32Fleet]

Originally Posted by swooshed

Going through the same exact issue on my F34. Open to diy flush the heater core but am not confident without a video or picture walkthrough. Do you happen to have one?

I have the same issue as everyone else.


IMO a plugged core would reduce total heat output to the system rather than ouput to one side. My money is it's a blend door issue.

The best way to flush the core is to flush it via the TO/FROM hoses leading from the coolimg system to the core. You'll have to remove the air box to gain access.
If you have automatic climate control you will have to disconnect the hose at the heater control valve leading to the core.

Just use a garden hose and maybe se a pump to circulate some cooling system cleaner through the core.

I would NOT flush the entire cooling system with cleaner because you'll never be able to get it all out from areas such as the engine block.

[Billfitz]

Having some cleaner left in the system wouldn't bother anything, but I wouldn't use it on the entire cooling system. If I confirmed that there was a blockage in the heater core I'd disconnect it from the system and rig a closed loop to it, using a garden pump to circulate cleaning solution through it for at least an hour. Then I'd flush it with water before reconnecting it to the cooling system. Just flushing it with the high pressure from a garden hose would probably loosen up most of what's clogging it without using a cleaner.

[CoopersF15]

Just adding my own experience. No faults thrown but the AC was providing cool air then shutting for no reason, and hot air come out of all other vents, causing the cabin to heat up like crazy of course.

BMW couldn't figure it out. Independent shop did figure it out. Fuse was replaced and has been working fine ever since.

[i7iQs]

What fuse did the garage replace?.
I have an e90 with same problem.
Passenger Side blows warm and drivers side blows cold. Actuators are working because I can see the little plastic thing moving. Coolant is fine and flushed the matrix too but still no heat

[F32Fleet]

Originally Posted by CoopersF15

Just adding my own experience. No faults thrown but the AC was providing cool air then shutting for no reason, and hot air come out of all other vents, causing the cabin to heat up like crazy of course.

BMW couldn't figure it out. Independent shop did figure it out. Fuse was replaced and has been working fine ever since.

Which fuse

[Aaroona]

Originally Posted by dadecounty3051

Here's the rest

thanks for the info. I will have a look again at this tomorrow - we are about to head into winter here in NZ, so it had crossed my mind to check on it.

Originally Posted by F32Fleet

Which fuse

Did you find out which fuse?

[russkie]

Im having the same issue left side isnt't as warm has the passenger side and its summer here and im dying with the heat

[Solidjake]

Hey guys, I bought the part but I'm still unsure which specific one controls the DRIVERS side flap. The vent by window gets hot whereas everything else is perfect.

Also is the actuator accessed by the drivers footwell or passenger footwell?

[Revoltos]

They are mounted on both sides of the HVAC mate. Think there is 9 in total. Depending on what side is at fault here will determine which side to go for.

[rlesko]

I had this problem on my car many years ago so thankfully it was under warranty. I’ll dig into my receipts to see what they replaced - but if memory serves it was an electrical issue with the board that controls the heat.

EDIT1: the part that was replaced was 64119301309 which has been superseded many times now but its the "Control unit f autom.air conditioning" according to realoem. And I had the same issue, NO HEAT from one side. In my case, it was passenger side without heat, driver side heat was good.

EDIT2: For some reason they also replaced 64119229486 in conjunction with it. No idea why.