[icekxd]

Hi guys,

I have an issue with heating in my car. It is currently the middle of a cold winter here in Europe and no heat is a big oof. I had an issue with the thermostat some time ago and carried out the replacement of Tstat + water pump. Those with the n55 engine know how crazy that job is (literally no room to reach the tstat without removing a ton of stuff.

I have carried out the bleeding procedure correctly and I can immediately see the difference in the engine reaching operating temp much faster. However, the heating issue stayed the same.

Turning the temp dials to full heat with auto and A/C off will blow only very mild/warm air. Turning the blower to 5 or more will blow gradually colder air. While the car is idling and blower is set to 1 or 2 it will blow warm cozy air, but as soon as I turn up the blower it gets colder.

Fluid temperatures are all in their correct ranges, there is sufficient coolant in the system and it is properly bled and pressurized. Both hoses running to and from the heater core are hot when the engine's up to operating temp and heat is on, but turning the blower to full and air temp decreasing I imagine is indicative of the heater core being plugged/obstructed.

I have ran several service functions with ISTA diagnostics that have returned no faults/irregularities. Calibration of flaps also changed nothing.

Heat selection next to the vents is fully set to heat.

I suspect it could also be the shut-off valve, anyone have any experience on this and whether there is any way of checking it?

Worst case scenario is the heater core being shot - how can I check it to be fully sure?

My car is a 2015 model with about 70k miles.

Many thanks for any clues/heat in advance

[MarcoZandrini]

When did this problem show up? If it's after the changing of the thermostat it could be that there's air in the heater. How hot are the heater hoses?

[icekxd]

Originally Posted by MarcoZandrini

When did this problem show up? If it's after the changing of the thermostat it could be that there's air in the heater. How hot are the heater hoses?

I’ve had this problem for about a month before the replacement. After the replacement it seems as if the air has gotten slightly warmer, but still far from expected. Other points worth noting is that with the engine running the centre driver vent always blows cold air, unless I leave the car idling when warmed up, the vents will blow equally warm air.

Both heater hoses reach hot temperatures, but it seems that one is slightly colder, which I imagine is the return hose.

[MarcoZandrini]

Ok, I'm wondering if there's aflap that's not being activated. Why? T%he hoses are hot so coolant is flowing. I'd have the climate control module (IHKA in BMWspeak) scanned for issues.

[icekxd]

Originally Posted by MarcoZandrini

Ok, I'm wondering if there's aflap that's not being activated. Why? T%he hoses are hot so coolant is flowing. I'd have the climate control module (IHKA in BMWspeak) scanned for issues.

I have carried out the flap recalibration process.

It may be worth noting that I have retrofitted the IHKA to an LCI panel (the one with white display) but besides it throwing a code (panel mismatch) it works perfectly fine. I have tried putting the original panel back in since I still have that and nothing changed.

[johnmcb]

I have exactly the same problem now with my 16 M235xi, 70K miles. What was the eventual fix for your car?

[icekxd]

Originally Posted by johnmcb

I have exactly the same problem now with my 16 M235xi, 70K miles. What was the eventual fix for your car?

I did no further diagnosis as the winter ended pretty quick and I somehow lived through it in a cold car. I decided that I would fix it before the next winter, but I sold the car in the meantime as I got a banging deal on the G42.

If you can smell coolant inside the cabin with heat on I'd suggest checking the heater core for vacuum or coolant leak. Unfortunately though, if necessary, replacement is a real PITA.

In case you can't smell coolant inside the cabin, I read on another forum that some people suggest "flushing" the system through the heater hose inlets to possibly unclog the heater core.

Whatever you do- good luck and feel free to post your results here

[vintagevrs]

Has anyone got a fix for this? Plenty of posts about the topic but no fix from what I have seen?

Are people selling the car on rather than dealing with it I presume?

[icekxd]

Originally Posted by vintagevrs

Has anyone got a fix for this? Plenty of posts about the topic but no fix from what I have seen?

Are people selling the car on rather than dealing with it I presume?

What's the issue you're facing? Maybe your thermostat failed?

[vintagevrs]

Thanks for the reply.

I have seen numerous posts with exact symptoms I have in different fxx cars.


I have an f22 m235i. UK car so driver side on the right. The heating system works perfectly for passenger side, hot blows hot, cold blows ice cold and everything perfect.

However on the right side of the car, the car will blow cold air conditioned air perfectly but the hottest it will blow is barely lukewarm.

I have read it could be a blocked heater core, which I am unsure of as the passenger side gets perfectly hot air and I presume the both sides pull air from the same core, but I'm a bit grey here.

Other option is a blender door/actuator not doing it's thing. However when I change the right side temp and have some trim removed I can see the actuator moving. Also the temp does change from ice cold, to mild air.

Maybe there's another blend door somewhere, or the actuator is moving but the door mech inside isn't moving correctly.


Any help appreciated 👍

[icekxd]

The heater core does not split the air in any way. There's only an intlet and outlet hoses that run to and from it.

The part you see with the trim removed might not necessarily be the one you're looking for, or the fact that it moves does not necesarily mean that the flap moves as it should. The actuator can either fail completely or the mechanism might stop working correctly.

Are you able to run a flap recalibration process via ISTA?

[vintagevrs]

Thanks for the reply. Missed it.

I used a endoscope camera and checked flap operation from inside. The left side (passenger Uk) works fine and heat operates perfectly from there.

From what I can see on the camera, flaps for all functions operate the same way for both sides of the car.

I have not scanned the HVAC unit for calibration.

Still an issue for me unfortunately.

Car was recently serviced by a specialist and they reckon it's a flap issue and dash needs to come out and left that with me. I'm still not so sure.

[MarcoZandrini]

These cars are rolling computers. Scan the IHKA (heat and AC controller) for codes.

[celsdogg]

I had a similar problem with my wife's F30. Computer never showed anything and all flaps worked properly.

Eventually I decided to reverse flush the heater core and a ton of crud came out. Heat works perfectly now. I've changed the coolant (with bmw blue and distilled) a couple times as routine maintenance and have no idea where the crud came from.

[vintagevrs]

Originally Posted by celsdogg

I had a similar problem with my wife's F30. Computer never showed anything and all flaps worked properly.

Eventually I decided to reverse flush the heater core and a ton of crud came out. Heat works perfectly now. I've changed the coolant (with bmw blue and distilled) a couple times as routine maintenance and have no idea where the crud came from.

Thanka for this. I suspect and hope this is the issue on mine.


Any tips for the job? Did you use any chemical/cleaners and let those dwell on the core or did you just flush it backwards?

Many thanks

[celsdogg]

i just flushed it backwards with a garden hose, no cleaners. The biggest clue that it was a plugged heater core was when that when the car's coolant was at operating temp the outlet hose from the heater core was only lukewarm to the touch.

A few random tidbits:
-i had both my sons help me; one controlled the hose flow (dont want or need full pressure from the hose to flush it out) and the other took care of the outlet hose that went to a bucket.
-On the outlet I attached vinyl tubing (from home depot) to get the length needed to reach the bucket.
-I could not get the hoses off the heater core. I detached them from the other end.
-my garden hose already had a male end repair kit on it. I removed it and cut the end off the hose so it was as flat and uniform as i could get it. then i simply held the garden hose to the heater core hose.

I initially planned to remove the hoses from the heater core and fit the vinyl tubing to the core directly, but even with hose pliers I could not get them off. after i was satisfied no other crud would come out, I attempted to blow out as much tap water as possible with my air compressor set to low PSI. Re-attached hoses, topped off with BMW blue/distilled water and then ran the self bleed procedure with the electric water pump. Its been hot ever since.

Others have had to do the same and some have used Prestone Radiator Flush. Good luck!

[vintagevrs]

Thanks for taking the time, that's really useful.

Cheers

[celsdogg]

sure, let us know how it goes for you if you can, good luck!

[vintagevrs]

Originally Posted by celsdogg

i just flushed it backwards with a garden hose, no cleaners. The biggest clue that it was a plugged heater core was when that when the car's coolant was at operating temp the outlet hose from the heater core was only lukewarm to the touch.

Just grabbed both hoses that feed the core after a drive and both are boiling hot.

Was your heating not working at all, or working fine on one side? My left side works fine, gets very hot if needed.

[celsdogg]

in my case the heat was even and the same from all vents. set to full hot, it came out around 100°F coming out the vent. After flushing, both hoses from the heater core were too hot to touch for long, and heat at the vent was over 170°F across all vents.

Sounds like your core is fine.

[vintagevrs]

So little update on this.

Got the coolant flushed today and the heat is now working on both sides. Garage said no crap came out but may have been air.

Makes little sense to me but delighted it's not a dash out job and I have a working heating system. May not be everyone's issue but sorted mine.

Cheers