[Zenith63]

Hi guys,

I have a 2007 e93 335i cabrio with a strange problem!

A year or two ago I started to have an issue where I would get into the car and put on the heat (or AC, doesn't seem to matter) and the blower would run perfectly however little to no air would come from the vents. If I turned the fan up to full speed I could hear the fan pushing hard and feel a trickle of air from the vents and a whistling sound (the trickle of air making it through a gap I'd guess). When it first started happening often I'd drive the car for a while and I'd hear a baffle/valve/flap of some sort open all of a sudden and air would start coming from the vents as normal.

The problem started intermittent like that, however now I can get no air from any vents (feet, face, window) at any time, as if a baffle/valve/flap has got permanently stuck closed. The blower sounds like it is running perfectly and speeds up/slows down as expected when I use the fan speed controls. I had it in with my mechanic (non-BMW) who tried replacing the various filters (pollen etc.) but no joy, he reckons the next step is rip out the dash and have a look at all the valves/flaps to see if any are stuck or not opening when they should be.


So wondering where to start troubleshooting this? Is there an easily accessible controller unit when I can stick a multimeter on and look for a voltage pulse to indicate that the controller is "good" and trying to open the flap but the servo is shot or flap stuck? I'm guessing there are various flaps, but probably only one that would prevent air making it to any of the outlets, is there a diagram of where these things are in the dash that I could take it apart myself some weekend?




Thanks!

[Zenith63]

While driving home in traffic today I miraculously started getting some air into the cabin. The oil temp had got up to 120Celcius (tends to be more like 100C while driving faster) and warm air started coming out of the vents onto the winscreen. Within about 30 seconds that air turned to cold (but not AC cold) air but continued to blow until I got home.

Wondering if there is a temperature sensor faulty somewhere or maybe the IHKA unit is shot and misreading sensor input?




Just in-case this is useful to any future readers, I came across this PDF http://www.shrani.si/f/2z/Eu/2cbNKAh...te-control.pdf which has some great info in it on how the climate control system is supposed to work, location of stepper motors etc.

[Zenith63]

Wonder if anybody has any idea if I was to buy one of the "basic kits" from here - http://www.bavariantechnic.com/buy.aspx - would I be able to see info from the IHKA such as it sending signals to the servos to control the air flaps or odd readings from sensors, maybe therefore being able to figure out what is wrong?

[Flyboy161]

Look up Bimmergeeks. He's a wiz with software. But before you do, a question: are setting up the system on AUTO? Have you tried manual control of the vents?

[Zenith63]

Hey thanks for replying.

Yeah spent a lot of time trying all the various different climate settings over the last year or two having this issue .

Randomly, after I began to get air to the windscreen on Monday, yesterday I went for a long drive and all vents started letting out air as normal and if I changed from say 16C (full cold) to 28C (full hot) I could hear various flaps open/close and the air output change. The air was not hot that was coming out though, even though the engine oil temp was at 100C (which I think is normal for this car).

This makes me think that there is nothing wrong with the servos/stepper-motors themselves, that maybe there is a temperature sensor giving poor readings or that the IHKA unit is just gone faulty? Could it be as simple as the servos not being properly keyed to the IHKA, maybe it is attempting to open/close the wrong servos?

I've reached out to Bimmergeeks and am getting a cable ordered before we can do some diagnosis, see if there is anything obvious there!

[Flyboy161]

He's a good guy, and I'm sure he will help you out. I'm still getting used to mine, but I don't think your problem is indexing of the stepper motors. I know for my car, I have to be out of automatic climate control to have the ability to regulate where the air is going. Except for defrost of the windscreen. Push that button and ALL air goes to the windscreen. The rest of the time, the IHKA is continuously regulating the air flow everywhere but the main vents.

[Zenith63]

Hi guys,

Just wanted to update this thread for those that come across the same issue in future.

As well as this issue with the blowers/AC I've been having an issue with the car losing coolant. Initially it was a cracked pipe which the garage repaired, however the car still goes through a litre every few months.

Anyway, the A/C and heat had been in a phase of working perfectly for the last couple of months, then the low coolant light came on again. I topped it up, but a couple of days later I noticed that the A/C and heat were not working again - same story where the blower was going but no air was coming out the outlets. The coincidence of the coolant being low and this issue happening at the same time reminded me of a thread I read a couple of years ago about bleeding the radiator system after a coolant change, and something about air getting stuck up in the climate control system if this was not done.

So I did the coolant bleed process (rad cap off, heaters on full hot, fans on low, key in ignition and press the accelerator for 10 seconds), lots of air bubbles came through and afterword the heating and A/C were working perfectly. Simple as that!

[weehe126]

You are saying the AC didn't work until you bled the coolant system? I'd understand the heat, but AC seems odd.

[Zenith63]

The thing is I think the car was actually creating cold/hot air, it just wouldn't let it out the outlets. You could hear the blower going, but it sounded like there was a flap closed in the dash and the air was blowing against it.

When I'd turn the A/C on, I could hear the A/C unit kick in and the blower going but no cold air would come out of the outlets. In the winter when turning it onto hot air, I'd have the same effect where I could hear the blower going but no air coming out of the outlets, or maybe a tiny trickle of hot air. Sometimes sitting with the car idling for 15 mins or so would cause whatever flap was closed to open, and hot air to come out. Very bizarre.

So I'm wondering if there is a sensor in the coolant that won't open the outlets until the air is hot/cold enough or something along those lines.

[gbalthrop]

Originally Posted by Zenith63

So I'm wondering if there is a sensor in the coolant that won't open the outlets until the air is hot/cold enough or something along those lines.

Does anyone know what the function(s) of the "Coolant Pressure Sensor," coded B8 in the Bentley Manual is/are? This sensor is (according to Bentley) located under the coolant reservoir and electrically connected to JBE, as is the AUC sensor. It is NOT mentioned in the A/C documentation in Bentley or in the BMW pdf OP posted (that I have noticed). Thank you for that pdf Zenith63!!

For some unexplained reason, the "Coolant Pressure Sensor" is shown in circuit diagram for the "Heating and air-conditioning functions" page ELE-247 of Bentley with NO mention of its function ANYWHERE in Bentley (I used wordsearch on the pdf Bentley version). Is it possible that has some connection to flakey flap operation when coolant system has NOT been bled?

Also, both the Bentley and BMW documentation DO mention a "Heater valve" (item 24 in IHKA circuit diagram), also referred to as a "Water valve" in Bentley, ELE-247. Bentley states that the valve is located at the left rear of the engine compartment (presumably near the expansion valve & refrigerant lines passing through the firewall). I don't find any such valve in the RealOEM parts catalog.

I don't see any such valve on my 2007 328xi, although I did NOT remove the microfilter housings and carefully trace the two heater hoses looking for it. Occurs to me that COULD have some bearing on both loss of coolant & failure of air delivery, depending upon how ECU is programmed.

Finally, does anyone know what the function of the "Ventilation Temperature Sensor" is? Does this perform somewhat the same function as the old heater core temp sensor that would prevent blower operation (except for defrost) until coolant temp reached say 50C?

George

[Vachoo]

Zenith63 any luck with the issue mate?
I have exact the same on my 330D and have no idea what to do next.

[gbalthrop]

Originally Posted by Vachoo

Zenith63 any luck with the issue mate?
I have exact the same on my 330D and have no idea what to do next.

Did you do a forum search on "Exact Same Issue" -- you'd get thousands of hits (and NONE of them would be helpful).

If the blower is running and you have NO air delivery from ANY of the Vents: windscreen, facia, footwell, then the motorized flaps are NOT working or are NOT being activated. INPA and ISTA (BMW diagnostic software) are able to Test/ Activate each of those flaps, or to show existing flap position to confirm the apparent fault, and try to determine the cause of the fault. Here is the TIS circuit diagram for what I would think is your 330D E90 IHKA system Functions. The 8 flap motors are shown on the far-right side of the schematic:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

If you examine the schematic carefully, you will note that each flap motor has:
1) 12V+ Power supply;
2) Ground (provided by IHKA module); AND MOST IMPORTANTLY:
3) Control via LIN_BUS from the IHKA

Understanding that BUS is key. The BUS connections to the Flap Motors are in series, so that if there is a problem in the BUS (Yellow wire) between the IHKA and the Defrost Flap Motor, NONE of the flap motors will be activated by the IHKA. If there is a fault in the BUS between the Defrost Flap Motor and the Fresh Air Recirculation Flap Motor, the Defrost flap will work, but the others downstream in the BUS will NOT, etc.

So start diagnosis by pressing the Defrost button on the right of the IHKA control panel, listen for flap noise, then try Recirculate Flap, etc.

Does the IHKA (Climate Control) panel light & function as normal, including the buttons that direct air to Footwell or Defrost? You could have a bad ground (common ground provided by IHKA for ALL 8 flap motors), or a bad power supply to IHKA per this schematic:
https://www.newtis.info/tisv2/a/en/e...system/hpunewB

Just as a quick check, you might try manually changing air distribution flap positions by pressing the air distribution buttons, Defrost, etc. with engine running (higher system voltage) and waiting ~ 60 seconds for flap system to operate. If NO change, try next button.

Please let us know what you find,
George

[Zenith63]

Originally Posted by Vachoo

Zenith63 any luck with the issue mate?
I have exact the same on my 330D and have no idea what to do next.

In my case I seemed to be having a variety of issues over a few years.

At one point I was getting no hot air to the cabin. It's been a long time, but I believe it turned out to be a coolant temperature sensor of some sort that meant the engine was never getting up to a decent temperature (I'd get hot air if I left the car stopped and running, but as soon as I started driving the engine temperature would drop and I'd lose warm air). Got that fixed, all good.

Then I had an issue with losing coolant (turned out to be a seal somewhere) but when it got too low I'd stop getting heat to the cabin. Fixed the seal, ran the coolant bleed process a few times and I had heat back again.

Then the last one was the blower running perfectly, the IHKA control panel looking like it was working perfectly, but the motorised flaps were just never opening so you'd hear air blowing against them trying to get to the outlets. In the end I bought a second hand IHKA control panel on Ebay, fitted it and as soon as I turned on the car all the flaps opened! Now whether the old IHKA unit was actually faulty or had become decoded from the flap motors through all the messing trying to fix the other issues I'm not quite sure, but the replacement fixed it either way.


Hope that helps!

[Pa-Beer's e90]

Originally Posted by gbalthrop

Did you do a forum search on "Exact Same Issue" -- you'd get thousands of hits (and NONE of them would be helpful).

If the blower is running and you have NO air delivery from ANY of the Vents: windscreen, facia, footwell, then the motorized flaps are NOT working or are NOT being activated. INPA and ISTA (BMW diagnostic software) are able to Test/ Activate each of those flaps, or to show existing flap position to confirm the apparent fault, and try to determine the cause of the fault. Here is the TIS circuit diagram for what I would think is your 330D E90 IHKA system Functions. The 8 flap motors are shown on the far-right side of the schematic:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

If you examine the schematic carefully, you will note that each flap motor has:
1) 12V+ Power supply;
2) Ground (provided by IHKA module); AND MOST IMPORTANTLY:
3) Control via LIN_BUS from the IHKA

Understanding that BUS is key. The BUS connections to the Flap Motors are in series, so that if there is a problem in the BUS (Yellow wire) between the IHKA and the Defrost Flap Motor, NONE of the flap motors will be activated by the IHKA. If there is a fault in the BUS between the Defrost Flap Motor and the Fresh Air Recirculation Flap Motor, the Defrost flap will work, but the others downstream in the BUS will NOT, etc.

So start diagnosis by pressing the Defrost button on the right of the IHKA control panel, listen for flap noise, then try Recirculate Flap, etc.

Does the IHKA (Climate Control) panel light & function as normal, including the buttons that direct air to Footwell or Defrost? You could have a bad ground (common ground provided by IHKA for ALL 8 flap motors), or a bad power supply to IHKA per this schematic:
https://www.newtis.info/tisv2/a/en/e...system/hpunewB

Just as a quick check, you might try manually changing air distribution flap positions by pressing the air distribution buttons, Defrost, etc. with engine running (higher system voltage) and waiting ~ 60 seconds for flap system to operate. If NO change, try next button.

Please let us know what you find,
George

Hi George. Thank you for your post. I am sure I have the same issue. Some background: I was doing an oil change service for the first time myself on the car. During my reading up and watching how-to Youtube videos I stumbled on how to test the water pump and how to bleed the coolant system procedure for cars fitted with electric water pumps. I did the procedure being under the impression that my car has an electric water pump. I got all worried when the pump did not come on after depressing the accelerator pedal for 12 seconds. Tried it several times. I called the guy who serviced my BMW previously and he informed me that this model is not fitted with an electric water pump but with a mechanical pump so I need not worry. I completed the service, reset the service intervals but when I drove the first time the blower issue as described in the thread popped up. I called the guy again and he advised that I replace the resistor mounted to the blower motor which I did. The problem persists and here I am after much research. I am not sure but I wonder if attempting the water pump test had anything to do with what I am now experiencing. especially in the light that everything worked flawlessly before? I know I know I should have let someone else or a dealership do the service but I just could not afford that now and the guy who usually did it affordably had relocated. Any thoughts advice will be greatly appreciated.