Heater Control Valve 4.8is Cabin Temperature

[Clavurion]

Originally Posted by andrewwynn

The cabin sensor is in the control panel. Has a fan to pull in air. I think there is only one sensor there. I'm not are about left v right I haven't seen left v right sensors other than the heater core temps so maybe it uses those temps and some math.

Correct, only one sensor in IHKA. Separate sensors on the heater cores.

[andrewwynn]

Out of morbid curiosity I ran the heat set to 85, for about 30 minutes driving. Recirc on and though the sampling sensor was able to get to 83, the cabin was about 81° with fan still maxxed. If I turned down the temp the heater caught up with demand about 81-82°.

(Indicated by the auto fan speed dropping)

Ambient was 30° at the time. Maybe in TX the car can be heated to 85, don't see it happening in Wisconsin during winter. I'm quite happy with cabin set to and actually 73°.

[X5M-ISH]

Originally Posted by Clavurion

Correct, only one sensor in IHKA. Separate sensors on the heater cores.

Yes! That diagram rocks. The Heat Core Temp Sensors; driver side and passenger side. Where are those things buried?

For diagnostic I use INPA.

[Clavurion]

Originally Posted by X5M-ISH

Yes! That diagram rocks. The Heat Core Temp Sensors; driver side and passenger side. Where are those things buried?

For diagnostic I use INPA.

Both sensors behind radio/nav screen. Unlikely that those sensors fail. Check with diagnostics what they are showing. The figures should be quite close when demand on both sides is similar.

[andrewwynn]

I almost forgot to mention; my heart cores were 175 and the center vent was a punishing 169! I'm amazed.

In spite of A 140° difference between output in the dashboard and outside it was only able to raise the interior cabin 50°. I only did about a 35 minute test so maybe on a longer drive definitely with a higher ambient temperature I’m sure you could get it up to 85 inside. I don’t know anybody that would find that comfortable I think that the car never gets that hot and so people think it’s 85 is really probably 80.

I’m definitely not saying it’s not possible some people like it really really hot. most people will find 75° too hot if it’s cold outside and most people will find 75° cool enough when it’s hot outside.

This 85 thing just piques my curiosity something fierce.

[X5M-ISH]

I just got back from heading to the mountains and back. While driving, I used an infrared thermometer. Here is what I found (values of F):


IHKA set at 72 for both sides
IHKA inlets: Driver = 74 Pass = 74

Window vent: Driver = 74 Pass = 90
Mid level vent: Driver = 95 Pass = 173
Floor vent: Driver = 64 Pass = 90

Rear center console vent = 167

When I arrived at my destination I popped the hood while the engine running and measured the temp of five hoses. Being that the heater valve is a point of contention, these measurements are based off of that:

Top hose to firewall = 145
Bottom hose to firewall = 113

Top hose to radiator = 103
Bottom hose to radiator = 145

Radiator hose from water pump to top of radiator = 182

I digress that the window and foot vents could not be properly measured i.e. aiming the thermometer straight into the vents. However, the near vent surface areas do show a thermal gradient and is consistent with the driver side being much cooler than the passenger side.


Tomorrow when there is time and day light, I'll run the truck to operating temperature with the heat control valve in the engine bay unplugged and take readings again. Though, if anything stands out to anyone from the numbers above, feel free to add!

[andrewwynn]

I did a test yesterday where when at maximum heating I got numbers similar to what you are seeing on the passenger side when set to 72. I'm seeing more like what seems to be a stuck open heater valve to the passenger side.

With the control set to 72 you should see numbers like 90 in the floor vent and maybe as high as 80 in the dash vents.

Do you have a scanner that will report the heater core temps and the state of the valves? Also when the temp has achieved steady state you should hear what sounds like a heart beat from the dash; it's the two heater valves opening and closing in quick succession.

Lub dub. Lub dub. Lub dub.

If you only hear lub. Lub. Lub. One of your heater valves is stuck.

If I can find a 9v battery for my thermo gun I'll take some measurements of my heater outlets and give you some control to work with

[X5M-ISH]

Originally Posted by andrewwynn

Lub dub. Lub dub. Lub dub.

No Lub dub love. I didn't hear anything XD. However, I have some fresh numbers monitored in real-time via INPA. Now...the heater control valve was unplugged as the dude above suggested I try. So I tried it. One thing I can not do is drive around and try and monitor values on my laptop. The USB cord is too short to run over my legs to set the computer on the pass seat. I took a bunch of photos, but here is the gist and everything was conducted while the truck parked (i.e. no engine load, water pump at idle, no air through the rad etc.). Monitoring of the climate control unit:

ANALOG F1

Engine temp: 206 F
Outside temp: 45 F
Inner temp sensor: 70 F
Evaporator sensor: 73 F
Heat exchanger sensor LEFT: 178
Heat exchanger sensor RIGHT: 180
Latent heat storage sensor: 149


CONTROL VALUES F2


Temperature INKA control pre-set: 68
Temperature INKA control pre-set: 68
Inner temp sensor: 70
Set value Y left: 56%
Set value Y right: 56%
Heat exchanger RATED temp left: 145
Heat exchanger RATED temp right: 145
Set value heat exchanger left: 0%
Set value heat exchanger right: 0%


I then measured the four hoses that connect to the heater valve in the engine bay with the infrared thermometer:
Top hoses: 175
Bottom hoses: 164


The hoses show a matching temperature to each relative side of the heat valve with it unplugged. I then plugged the heater valve back in to watch the changes in INPA. A few of the values began dropping, but not as quickly as I was hoping and I think this is mainly due to no airflow through the engine bay and radiator. So this is where the testing ended.

On a side note, I completely disassembled the INKA unit and found more dust wedged all over the small resistor that hides behind the inlet grill and cleaned it all out.

I'm heading to the mountains again on Saturday so I'll drive with the heater valve unplugged to see if the driver side temps fall off again. I'm starting to suspect that this is the problem because both left and right heater cores look fantastic and there were no fault codes stored for the climate control unit.

[andrewwynn]

180 is way way WAY too hot for the heater cores.

See mine with steady state of 73 in my cabin the heater cores are about 120.

Also I took the two pictures a second apart. The valves should be tapping open and closed about once a second. If you listen close behind the steering wheel (LHD) you should hear the valves tapping open and closed. It sounds almost exactly like a heart beat.

It was bugging me for more than a year until I finally had my foxwell and was able to scan realtime data and happened into the HVAC module and found the heater valves.

Was I happy to see them open and close in m exact syvc with the heartbeat.

[X5M-ISH]

I'll have to see if there is an option in INPA or BMW Scan Tool to see the valves open/close in real time.


Today with some good weather, I decided to install a new heater core valve. The prior unit was an OEM/Bosch with the new one being a no-name auto parts store type. With the engine cold, I pulled off the three hoses and maybe a half cup of coolant was lost during the swap. I was anticipating much much more than that or is this about normal?


Anyhow, the swap takes all of five minutes and I bled the coolant system. While the engine running I monitored the temperature of the center dash vents with my infrared thermometer. The center vents were right around 138 F with the climate control set at full hot. Significantly cooler than before PLUS both vents were reading around the same temps. So I call this tentatively fixed...until I drive it up the mountains tomorrow night and monitor again with the thermometer. Fingers crossed.