[jezmunky]

My 2016 F11 535d decided to celebrate winter by suddenly having no heat. I roamed around this forum and the internet and the consensus appears to be heater control valve which I have changed.

I thought I still had no heat but on checking carefully as the car warms up I discovered I do have a little bit of heat while the car warms up but when it appears to get up to temperature the heat very much leaves and blows freezing air into the cabin. There are no fault codes with a generic OBDII scanner and the antifreeze is between min and max. I suspect there is a thermostat somewhere that is dead or failing but no idea where it would be.

My car has the ancillary heater which incidentally I used the day the heater broke. Is this coincidence or are the systems linked more closely than I think? If I run the ancillary heater the pipes through the heater control valve get hot to the touch but they do not remain hot when the engine runs and the heat goes away. Incidentally the pipes do not feel hot when starting from cold and a small amount of heat does come out of the vents. What a complicated car?!?

Does anyone have any masterful ideas before I get BMW involved?

Thanks in advance! There's 30cm of snow on the ground.

[Johnkwick]

Oh so you have changed the heater control valve already? I have similar problem with you which is written in this post: https://f10.5post.com/forums/showpos...8&postcount=17

I haven't change the heater control valve but the pipes which located after heater control valve was hot (to be honest I could not determine whether it's hot because the heater control was working or because I live in tropical country and the engine already in operating temp range so it's hot anyway). Regardless the temp outside, I always set in 23C, in auto mode. But now it's always blowing the coldest air (16C), condensation on the outside bottom part of windshield, and auto mode isn't reliable as the conditioner always pushing coldest air so the car will tell the system to blow very little air

[jezmunky]

It turned out that despite numerous efforts to bleed the system using the ignition on and accelerator pedal pushed for 10 seconds with fans on slowest setter and full temperature selected that the car had not bled air out completely. I drove for about an hour over a few days with still no heat and then when driving to BMW the car magically bled / fixed itself. No problem as it was also having the EGR recall carried out which went about as well as expected... big list of things BMW suggest fixing plus intake manifold flap apparently stuck so they give me back a car that pre EGR fix was remapped 535d and after their work felt significantly slower than my partner's 320d GT... booked back in with BMW and within another hour of driving the flap has unstuck itself and I'm back to lethal amounts of power still in -12 centigrade... :-) I can't say I'm particularly enjoying ownership of this BMW. The constant issues so far are making me think to sell it and get an EV under warranty.

[vncung]

Last time my F25 had no heat was due to
Thermostat stuck in open position.
Replacing the thermostat fixed my issue.

[Johnkwick]

Replaced my heater valve, now the heat is coming back BUT only on driver side.

I tried to set both driver and pax climate setting to 28C, driver side was hot, passenger side wasn't that hot just tad above cold and below hot. But when I tried to set driver side to 24C and pax side to 28C, pax side didn't blow any hot air.

On re-circ & auto setting I also noticed that the windshield on pax side has condensation spots on the bottom which means it was blowing cold air.

I just replaced the heater valve, what else could be the suspect?

Pic from ISTA
Pax side (left side) and driver side (right side) climate temp set to 28C after 3 min






Pax side (left side) 28C, driver side (right side) 24C after 3 minutes



Strange thing is that the left heat exchanger didn't see any significant increase in temperature compared to right heat exchanger. Instead of getting the hot water from the coolant line, I think the left heat exchanger was getting the heat indirectly from the right exchanger. This should explain why the driver side was very responsive to the climate setting. i just replaced the heater valve, could it be caused by clogged left heat exchanger line?

[Supahone]

When you try to prime the heater core using the proceedure of turning on the heat to the highest temp running at low fan and holding down the gas pedal for 5secs you should hear pump kick in. If you dont the water pump or heater valve are toast.

[Johnkwick]

Originally Posted by Supahone

When you try to prime the heater core using the proceedure of turning on the heat to the highest temp running at low fan and holding down the gas pedal for 5secs you should hear pump kick in. If you dont the water pump or heater valve are toast.

Yes I did the bleeding procedure shortly after I replaced heater valve and water pump was working

I opened newtis yesterday and learned that there's only 1 heater core but 2 heater core sensors in the air distribution box. So I suspected that the mixing flap for pax side is either toasted or needs to be recalibrated

[chipguy]

You should try vacuum fill the coolant. This will eliminate all the air pockets.