[MiniXP]

It seems like in my 335i I always have hot air blowing on my feet.

Yesterday it was 77 degrees out, I had the hvac set to 67 with the AC turned off. Cool air was blowing from the face vents, but down at my foot it was blowing hot air.

Does anyone else get this? Any idea why it does this? The auto climate control in general in this car seems not to work great. My e46 I used to just set it at 68 and forget it. I feel like in this car I'm always adjusting it.

[Johnny Boost]

Did you twist the dial between the center vents to blue?

[MiniXP]

Originally Posted by Johnny Boost

Did you twist the dial between the center vents to blue?

Yes, that controls the upper vents. I have that all the way to blue and it blows cold air out of the upper vents, but hot comes out of the foot vents.

I'm wondering if it could be heat from the engine that causes the air by the feet to be hot all the time. The engine does seem to put of quite a bit of heat

[fazman]

Originally Posted by MiniXP

Yes, that controls the upper vents. I have that all the way to blue and it blows cold air out of the upper vents, but hot comes out of the foot vents.

I'm wondering if it could be heat from the engine that causes the air by the feet to be hot all the time. The engine does seem to put of quite a bit of heat

Actually that Red/Blue dial is the actual temperature setting... the HVAC electronic controls below the radio is only trying to target the temp you want by varying the fan speed based on the temp from the Red/Blue dial on the vents.

[ThugzZ BunnY]

fazman that is 100% incorrect. the red/blue dial is to adjust the vents blowing in your face by a few degrees. that way the car can cool/heat quickly without getting the cold/hot air blown in your face.

[Efthreeoh]

OP, it could be a stuck module. Have you tried going to manual mode and selecting just the dash and windshield airflow positins to see if the air at the feet shuts off?

[STRMTRPR]

I had a similar thing occur to me as well. It was always hot around the leg area even when i had AC turned off. Even my keyfob was hot at times. Oddly it went away when i did a engine oil change. Are any codes coming up?

[Wolf 335]

Your issue is the heater core valves located in the engine compartment.

Had exact same issue on my E39 and one valve was stuck open.

Looking at around $200-300 Canadian for that part.

[MiniXP]

Originally Posted by Efthreeoh

OP, it could be a stuck module. Have you tried going to manual mode and selecting just the dash and windshield airflow positins to see if the air at the feet shuts off?

Yes, I can shut off the feet vents and if I turn the temp lower it turns the foot vents off automatically.

It almost seems like the temp is just calibrated wrong or something. When it is almost 80 out I shouldn't need to turn the temp down to low 60s just to stop hot air from blowing out the foot vents.

[MiniXP]

Originally Posted by Wolf 335

Your issue is the heater core valves located in the engine compartment.

Had exact same issue on my E39 and one valve was stuck open.

Looking at around $200-300 Canadian for that part.

Any advice on further steps to diagnose this?

[Wolf 335]

Originally Posted by MiniXP

Any advice on further steps to diagnose this?

My diagnosis was from a private bmw shop. It was a while back and I can't recall how mechanic diagnosed it.

I do remember him saying that I was lucky it was stuck this way, because in some cases (depending on the valve position) you don't get any heat which can be an issue in the winter.

Does the heat blowing at your feet stop once you turn on A/C?

Have you had you car scanned for any faults?

[MiniXP]

Originally Posted by Wolf 335

My diagnosis was from a private bmw shop. It was a while back and I can't recall how mechanic diagnosed it.

I do remember him saying that I was lucky it was stuck this way, because in some cases (depending on the valve position) you don't get any heat which can be an issue in the winter.

Does the heat blowing at your feet stop once you turn on A/C?

Have you had you car scanned for any faults?

Yea, not getting any faults. I'll have to check again to see if there are any shadow codes, but I don't think there were.

When I tried to do some more searching I saw a lot of people have the cold air only issue.

[Efthreeoh]

Originally Posted by Wolf 335

Your issue is the heater core valves located in the engine compartment.

Had exact same issue on my E39 and one valve was stuck open.

Looking at around $200-300 Canadian for that part.

There are no heater core valves in the E90.

[patents]

Originally Posted by fazman

Actually that Red/Blue dial is the actual temperature setting... the HVAC electronic controls below the radio is only trying to target the temp you want by varying the fan speed based on the temp from the Red/Blue dial on the vents.

The electronic controls do more than vary fan speed. They do adjust the temperature of the air and the location (vent/footwell). I leave the dial by the vent in the middle year round. And the air coming out in the summer is a lot cooler than the heat coming out in the winter.

Try it. When it's 100 degrees put the little vent dial all the way to hot and set the HVAC controls to 60. I guarantee the car will cool off. If the vent dial was the sole control of air temperature, you would have full blast heat.

Also note that you can operate the HVAC in manual mode. If you take it off auto, the temp dials will change the temperature of the air (instead of the target cabin temp) only.

The little dial by the vent is for minor adjustments for just those vents in case you want heat in the car but cool air on your face. My old 80s Honda had it too (but it mechanical not electronic).

The logic behind automatic HVAC is actually rather complex.

[patents]

Originally Posted by MiniXP

It seems like in my 335i I always have hot air blowing on my feet.

Yesterday it was 77 degrees out, I had the hvac set to 67 with the AC turned off. Cool air was blowing from the face vents, but down at my foot it was blowing hot air.

How does it work in full auto mode?

With the A/C off, the air temp can only get so low, and the engine will warm it up a bit.

Try putting it on recirculate and see if that makes a difference.

And maybe it's that way by design. I'm just brainstorming here, but a good way to dehumidify air is to first heat it and then cool it. If you manually turn the A/C off you don't get the cooling.

[fazman]

Originally Posted by patents

The electronic controls do more than vary fan speed. They do adjust the temperature of the air and the location (vent/footwell). I leave the dial by the vent in the middle year round. And the air coming out in the summer is a lot cooler than the heat coming out in the winter.

Try it. When it's 100 degrees put the little vent dial all the way to hot and set the HVAC controls to 60. I guarantee the car will cool off. If the vent dial was the sole control of air temperature, you would have full blast heat.

Also note that you can operate the HVAC in manual mode. If you take it off auto, the temp dials will change the temperature of the air (instead of the target cabin temp) only.

The little dial by the vent is for minor adjustments for just those vents in case you want heat in the car but cool air on your face. My old 80s Honda had it too (but it mechanical not electronic).

The logic behind automatic HVAC is actually rather complex.

I'll need to experiment with this. Thanks for the info...

[motoguy128]

Originally Posted by patents

way to dehumidify air is to first heat it and then cool it. .

unless you have a "face & bypass" setup (which some cars might have) you are usually better off cooling the air first, then reheating to get the cooling coil as cold as possible to remove the most moisture from the air.

This is how all commercial HVAC systems are configured. You cool the air to a target setpoint to manage airflow and reheat to maintain room temperature. If the room needs maximum cooling, you provide no reheat and max. airflow. To save energy, you can recover heat from the condenser on the central cooling plant.

[MiniXP]

I was playing around with my temp settings and found I can make the feet vents blow cool air, I just have to turn the temp down way further than I should need to to get them.

It was 70+ degrees outside and the car was fairly warm. I set the foot vents to always be on, AC off. Driving around with the temp set at about 67 there was warm air blowing on my feet. I turned the temp down to 60 and cool air finally started to blow out.

It seems like the temp may be calibrated wrong or something. Does anyone know of a way to reset this in INPA or some other way?

[clubs07]

Originally Posted by MiniXP

I was playing around with my temp settings and found I can make the feet vents blow cool air, I just have to turn the temp down way further than I should need to to get them.

It was 70+ degrees outside and the car was fairly warm. I set the foot vents to always be on, AC off. Driving around with the temp set at about 67 there was warm air blowing on my feet. I turned the temp down to 60 and cool air finally started to blow out.

It seems like the temp may be calibrated wrong or something. Does anyone know of a way to reset this in INPA or some other way?

Reenacting an old post here. Did you manage to find what the problem was? I have the exact same issue

[gbalthrop]

Originally Posted by clubs07

Reenacting an old post here. Did you manage to find what the problem was? I have the exact same issue

Suggestions:
1) Do Forum Search: "exact same issue".

2) When that doesn't get any reliable information:
a) get Fault Codes read in IHKA & JBE Modules & report them HERE.
b) If you don't have a Scan Tool or Diagnostic Software (INPA/ISTA) that can read fault codes in those modules, try Advance Auto, AutoZone, etc. for free code reading.
c) When you report Fault Codes here, please indicate exactly WHAT does NOT work as it should, the settings selected on Climate Control Panel, and what happens a minute after selecting MAX on the Driver side T-Stat (which SHOULD over-ride Control Panel settings).
George

[clubs07]

thanks for your input.
I have ISTA P and ICOM. Have the lastest firmware update installed in all modules.
Test shows no errors.
This is a very specific issue, as the previous message I quoted.
I did search the forum. I know culprits could be water valve or the seal from the steering column at the firewall causes similar complaints.
However in my case the footwell fan does blow cold air when I drop the temp below 65F and I was wondering if the user I quoted who had the same issue found the culprit which would help me direct my attention to.

Originally Posted by gbalthrop

Suggestions:
1) Do Forum Search: "exact same issue".

2) When that doesn't get any reliable information:
a) get Fault Codes read in IHKA & JBE Modules & report them HERE.
b) If you don't have a Scan Tool or Diagnostic Software (INPA/ISTA) that can read fault codes in those modules, try Advance Auto, AutoZone, etc. for free code reading.
c) When you report Fault Codes here, please indicate exactly WHAT does NOT work as it should, the settings selected on Climate Control Panel, and what happens a minute after selecting MAX on the Driver side T-Stat (which SHOULD over-ride Control Panel settings).
George

I am going to reinitialize IHKA module and see if it helps.

Update: just tested again and everything seems to work fine footwell blowing footwell blowing cold air even at higher temperature settings as long as the cabin temperature needs to drop. Either was a normal IHKA behavior or was an intermittent issue seems to have resolved.