[relative4]

Hi, '08 E90 here. This is about the red-to-blue slider wheel dial control thingy between the center dash vents. Does anyone know exactly what it does, and how it does it? I ask because mine appears to be stuck full hot. The ambient temperature is mostly in the sixties (Fahrenheit) around here these days, and if the A/C is off and the slider on blue, the vents blow like 120F. Changing it from one extreme to the other appears to make no difference. Putting the A/C on full blast is barely able to bring the interior down to a comfortable temperature, and that's only for the front seats. The passengers in back are sweltering. My wife's basically identical '07 E90 does not have this problem.
No relevant codes. I have ISTA and Carly.

[IllSic_Design]

Sounds like hvac/compressor issues. The knob between the center vents is only to tune the air coming out of the vents in the dash. Regardless of what you have the knob set to, if you have the AC on full blast you should feel it in the car coming out of all the other vents, including the rear seat vents.

[relative4]

Yeah my bad, it's got nothing to do with the dash slider, which I now understand only affects the dash vents. The whole system is just blowing insanely hot. All vents. Ambient is currently 55F, and with the A/C off and the thermostat at its coldest, the air from the vents is uncomfortably hot. Like 100F, minimum. I got brave and turned the thermostat up to full heat, and the air from the vents was truly scalding. Like first degree burn hot. Obviously something up with either the blend door, or do these cars have a valve in the hose to the heater core?

[gbalthrop]

I presume the "thingy" you are referencing is the thumbwheel in the center of the dash facia? That thingy actually is the Front Stratification or "Mixed Air" Flap (there's one for the rear as well), to deliver "more or less cool air from the vents for the upper body area" [TIS] (via facia vents & windscreen vents). Here is the TIS circuit diagram showing the Eight (8) Flap Motors on the Right side of the Schematic:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

If you press the MAX button in the center of the Left Thermostat, you should over-ride any other settings, such as Defrost, and get max fan speed and maximum cooling (minimum air through the heater core). If THAT is NOT working as represented, then you either have an issue with the flap motor controls via the LIN BUS, or a refrigerant issue (low R-134a pressure/charge).

INPA has a screen when you connect to the IHKA Module which shows Flap Positions (Klappen Positionen), and you can also see Analog Port Readouts in another screen that show actual High Side pressure (~ 6 Bar off, & ~ 9 to 15 Bar when operating, depending upon conditions, as well as Evaporator Temp which should be in the 3C to 10C range if the compressor valve is allowing "pumping." I would expect that ISTA has something similar.

The Flap Positions screen allows you to see the change of position of each of the 8 flaps when activated, and the Refrigerant Pressure readout and Evaporator Temp readout confirms that the compressor, condenser & expansion valve are cooling the evaporator coil properly. If Pressure is high and Evaporator Temp is low, then if you are getting warm air from some/all of the vents, the Mixed Air Flaps are routing the cool air from the evaporator through the heater core. The Right & Left Mixed Air Flaps are the primary temperature regulating devices, controlled by the setting of the Right & Left Thermostats, so if you never get cool air, either your refrigeration system (R-134a charge most likely) has issues, or the R&L Mixed Air Flaps aren't flapping.

Try "exercising" (as opposed to exorcising ;-) all the flap motors by pressing all the little buttons with green LED thingys (air delivery vent selection, recirculation, Defrost, Temp controls min to max, and yes, the center of dash thingy.

If you have INPA running (ISTA normally installed after installing Standard Tools which includes INPA), I can get you connected to the IHKA module quickly and you can see the screens, which I can translate if your version is in German so you know which flaps are what, and which bar graphs are Evap Temp (Temperatur Verdampfer) & Refrigerant Pressure (Druck Kaltemittel).

BTW, even though the TIS circuit diagram linked above shows both a Water Valve & Auxiliary Water Pump, NEITHER is on most US E9x models. Mine does NOT have either, and AFAIK, no US model after 3/1/2007 has either, so temperature of air delivered from vents depends upon how much of the cool air from the evaporator is directed through the heater core by the Mixed Air Flaps.

George

[Efthreeoh]

Originally Posted by gbalthrop

I presume the "thingy" you are referencing is the thumbwheel in the center of the dash facia? That thingy actually is the Front Stratification or "Mixed Air" Flap (there's one for the rear as well), to deliver "more or less cool air from the vents for the upper body area" [TIS] (via facia vents & windscreen vents). Here is the TIS circuit diagram showing the Eight (8) Flap Motors on the Right side of the Schematic:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

If you press the MAX button in the center of the Left Thermostat, you should over-ride any other settings, such as Defrost, and get max fan speed and maximum cooling (minimum air through the heater core). If THAT is NOT working as represented, then you either have an issue with the flap motor controls via the LIN BUS, or a refrigerant issue (low R-134a pressure/charge).

INPA has a screen when you connect to the IHKA Module which shows Flap Positions (Klappen Positionen), and you can also see Analog Port Readouts in another screen that show actual High Side pressure (~ 6 Bar off, & ~ 9 to 15 Bar when operating, depending upon conditions, as well as Evaporator Temp which should be in the 3C to 10C range if the compressor valve is allowing "pumping." I would expect that ISTA has something similar.

The Flap Positions screen allows you to see the change of position of each of the 8 flaps when activated, and the Refrigerant Pressure readout and Evaporator Temp readout confirms that the compressor, condenser & expansion valve are cooling the evaporator coil properly. If Pressure is high and Evaporator Temp is low, then if you are getting warm air from some/all of the vents, the Mixed Air Flaps are routing the cool air from the evaporator through the heater core. The Right & Left Mixed Air Flaps are the primary temperature regulating devices, controlled by the setting of the Right & Left Thermostats, so if you never get cool air, either your refrigeration system (R-134a charge most likely) has issues, or the R&L Mixed Air Flaps aren't flapping.

Try "exercising" (as opposed to exorcising ;-) all the flap motors by pressing all the little buttons with green LED thingys (air delivery vent selection, recirculation, Defrost, Temp controls min to max, and yes, the center of dash thingy.

If you have INPA running (ISTA normally installed after installing Standard Tools which includes INPA), I can get you connected to the IHKA module quickly and you can see the screens, which I can translate if your version is in German so you know which flaps are what, and which bar graphs are Evap Temp (Temperatur Verdampfer) & Refrigerant Pressure (Druck Kaltemittel).

BTW, even though the TIS circuit diagram linked above shows both a Water Valve & Auxiliary Water Pump, NEITHER is on most US E9x models. Mine does NOT have either, and AFAIK, no US model after 3/1/2007 has either, so temperature of air delivered from vents depends upon how much of the cool air from the evaporator is directed through the heater core by the Mixed Air Flaps.

George

The thing is, once you use the word "thingy", my mind drifts to other things, and I lose interest in the thing you originally posted about.