String of HVAC Issues

[Mike in CT]

Unusual that I have had three HVAC problems show up at the same time.

1. Blower would only run constantly at full, intermittently at other speeds. Classic sword failure and a rebuilt unit fixed this.

2. Slight antifreeze leak out of heater core/AC drain and slight film formation on inner windshield. New core, plastic tubes and O-rings ordered from BMW. Dash comes out this weekend. Take advantage of the 50 degree weather while it lasts.

3. Right side middle vent only blows cold air. Right foot well is hot, so right section of heater core is getting hot coolant.

From this post:

http://forums.bimmerforums.com/forum...+stepper+motor

I assume that a likely cause may be a disconnected actuator rod associated with the right side mixing flap stepper motor or a broken motor tab. New motor is about $115. Anyone happen to have first hand experience and possibly some photos. Would like to get everything buttoned up by Monday and take care of any problem I have while the dash is out.

Thanks in advance

[Timm]

Sorry to hear that Mike, as you say, it sounds as if the stepper motor has fallen off or the linkage has popped off. I only recall seeing photo's of this problem on E32's - I'll have a look.

[Frankie]

2. Slight antifreeze leak out of heater core/AC drain and slight film formation on inner windshield. New core, plastic tubes and O-rings ordered from BMW. Dash comes out this weekend....

I have this issue too. Please let us know how your experience turns out. I would love to learn any tips, specifically regarding our '97 MY with dual airbags.

[Mike in CT]

A short clip of the operation of the face vent and odd three flap hot/cold mixing flap:

[Mike in CT]

Turns out the lack of warm air coming out of the right side face vent was due to the mixer/stratification flaps hanging up on a raised lip on the left side of the exit.

The three flap mixer flap assembly. The middle flap is actuated directly from a bell crank connected by a rod connected to a lever stepper motor. The lower flap (perforated) is actuated by a slot in the bell crank. The upper valve (covered with foam) is not directly actuated. It gets moved by the middle flap and by air coming from the heater core. Kind of a weird design.



Note the evidence of the scraping of the flaps against the side of the duct.





All others looked like this.



Sanding down the area to free up the flap movement work fine and took care of the problem.



In reconnecting the mixer valve actuation rod, I believe I over stressed the plastic bore on the middle mixer flap and fractured it. I appears the stepper motors close with some force. I noticed re-installation of the other non-lever type motors required also putting force on the flaps to get them to engage.

Anyway, removing the actual stepper motor from the transmission allows you to position the motor in an intermediate flap position for an easy installation.



The flap limits are self set after a few cycles of operation.

The damaged flap bore did not hold the bell crank in place and it would pop out of it's seated position after a few cycles of operation. Used ABS plastic epoxy to permanently hold it in place.

Bell crank.



Can also be viewed through floor vent outlet.

Using mechanics mirror to view the flap bore.



Bell crank.





It was very helpful running the IHKA system with the dash out and the instrument cluster, center vent, and IHKA control unit connected. Found the bell crank popped out and was able to fix that before putting everything together and was able to smooth the operation of a number of the valves by lubricating with a dry film PTFE spray.

The coolant leak I had did not turn out to be the heater core. Valley pan. At 214,000 miles the core was was replaced anyway for $127 from BMW. The film I had on windshield was from a leaking brand "X" AC evaporator I put in a couple of years ago. A mistake. BEHR evaporator put in.



Relating to a different post I made. I purchased three of the now supplied IHKA housing to dashboard gaskets to mimic the original. Cutting off the front sections of two in a taper and slicing the thickness of one in half.



Single gasket.

[Frankie]

Mike:

Since you have your dash out and you're playing with the air distribution box and flap motors, now would be a great time to experiment....

I have always wanted to attempt a retrofit of the '96-'99 E36 HVAC system into our 8's. Its fully integrated circuitry (no extra mother board) would yield not only a modern appearance but also simplified wiring. It's functions mimic the 8's controls in almost every way (dual zone temp, single fan speed control, etc.).

If you're so inclined, I would like to offer my support (via this forum and e-mail).

From my initial survey, all flap motors and the fan "sword" would have to be replaced. Of course there's the expense of acquiring all the parts, but if a salvage yard is in your vicinity, you could lift the whole system for cheap.

Just a thought....

[Mike in CT]

Frankie,

Sounds interesting, but everything is all buttoned up, functioning normally and I am back on the wintry road again. A daily driver.

Mike

[taylorpatterson]

Had a go with those damn bell cranks this weekend. Here's what I ended up doing since I didn't want to tear apart the whole dash just to get to the box and figure out how to glue that sucker in... just used the right sized grab washer, or whatever it's called. Works like a charm. Keeps the bell crank on the flap crank even though it's not glued into its socket. A bitch to get in there, not much working room but those with long thin fingers will manage well... did this on the right side too just in case this crap happens over there in the future. What flap does that lever that goes in the bell crank control again??? First pic is left bell crank before, see how it's jumped off its mount?

beforeLeft.JPGafterRight.JPGafterLeft.JPG

[EEDegreeToDrive]

NOT LOOKING FORWARD TO THIS ONE!!!
My E32 gets a coolant smell when the heat first turns on. In the last 6 years it has not gotten any worse, so I haven't touched it. I know at least one stepper/flap/linkage is broken, and the AC leaks slowly. With a 250K mile car I only drive every few weeks, it's tough to muster up the energy to overhaul the HVAC.
Me E31 isn't much better. Nearly impossible to keep it comfortable in the car. With the AC off, windscreen fogs; With windows open, headliner blows around. Hot-foot-from-hell syndrome resolved with a new HCV last year, but still haven't replaced the Aux water pump. While a minor nuisance to fuss with the controls all the time, I'm not looking forward to the month-long operation of fixing the HVAC and rebuilding the sunroof (even though I already have most of the parts).
Finally, my E34 525i winter-beater/DD has no air, AC leaks out in a few weeks. Considering just parking it for the season and taking it back out next winter. Ohhh, and my blower is shot in the E34; Having changed the blower in the E32, I know what is entailed but don't have the time...

[Mike in CT]

Good idea with the washer Taylor.

The lever that fits into the bell crank operates the perforated flap. Number 19 in this cut away of an e32 housing.



And called the "MIXING FLAP LOWER LAYER" in these images.

[taylorpatterson]

Thanks Mike - that helps. So before my bell crank washer fix I was getting hot always out of the center DRIVER side vent and also hot all the time from the defrost/side vents when the system was set to 'auto'. I'm troubleshooting multiple problems at the moment including not being able to start the car due to the alarm that keeps going off thinking it's being stolen and so it ignition defeats. But when I can get it started, I'll be able to test to see if the washer fixed my heat always on in center vent trouble.

[EEDegreeToDrive]

Thanks Mike - that helps. So before my bell crank washer fix I was getting hot always out of the center DRIVER side vent and also hot all the time from the defrost/side vents when the system was set to 'auto'. I'm troubleshooting multiple problems at the moment including not being able to start the car due to the alarm that keeps going off thinking it's being stolen and so it ignition defeats. But when I can get it started, I'll be able to test to see if the washer fixed my heat always on in center vent trouble.

Taylor-- Try unlocking from the passenger door. (EDIT: Sorry-- forgot not all cars have passenger locks)

Mike et al- That system diagram is a beautiful diagram; To think that was probably drawn by-hand in 1985 without the use of computers. Just another engineering marvel of these cars. Many American cars still have one cable-driven blender; This car seems to have at least 3 stepper-driven ones (driver side, passenger side, center-vent)

[taylorpatterson]

Try unlocking from the passenger door.

Riiiiiiiiiiiiiight... and how exactly do I do that?

[Timm]

Had a go with those damn bell cranks this weekend. Here's what I ended up doing since I didn't want to tear apart the whole dash just to get to the box and figure out how to glue that sucker in... just used the right sized grab washer, or whatever it's called. Works like a charm. Keeps the bell crank on the flap crank even though it's not glued into its socket. A bitch to get in there, not much working room but those with long thin fingers will manage well... did this on the right side too just in case this crap happens over there in the future. What flap does that lever that goes in the bell crank control again??? First pic is left bell crank before, see how it's jumped off its mount?

Good work Taylor - that should keep it working!

[Dr. T]

Taylor, what did you have to remove to gain access the bell cranks?

Re: Alarm....you must have the same problem mine has....if the key fob won't shut it off, then the car is immobilized. New batteries? I usually just have to keep trying...the sensor is in the rear-view mirror...but you have the homelink version???

[taylorpatterson]

Just had to take out the kick panels trim pieces and then you can manually open the floor head vent, which is the openening to the bell crank.

I had move the alarm out of the mirror and into the headliner a while back; to retain alarm function after replacing the mirror with a Compass/Homelink version. I quick spliced into the existing wiring there in order to feed the correct signals back to the alarm to arm/disarm it. Worked great for a year and a half, util I opened up the headliner again to run power for a new radar detector. Touching my splice wiring job made the alarm go off. It thinks it's locked (the LED acts like it's been locked and armed) and so any attempt to open the door or start the car sets off the alarm and imobilzes the ignition. Also, neither of my key fobs disarm the car and I can't reprogram them until I can get the alarm out of this state.

Removing the 15A fuse in the passenger side panel deactivates the alarm and allows me to start the car so no problem there.

I am going to redo all my wire splices with Posi-Tap splices for the correct gauge wire and try to reset the alarm, then reprogram my key fobs. If that doesn't work, I'll get out the soldering iron and do proper soldier splices. I wanted to avoid that because there is such limited space to work in up there but I may not have any choice at this point.

Any other way I can quickly reset the alarm besides letting the car sit with the batteries unplugged for a while?

[zebber500]

I have the same problem , kinda. I have hot air coming out of the drivers side of the center vent and the door vent all the time the air cond is on.Cold air from pass side vents. Think it might be the stepper motor for the drivers side? If so how do I get to it?I really don't want to remove the complete dash. This happened all of a sudden, one day everything worked good ,next day hot air from drivers side. I unhooked the batteries thinking it might reset the stepper motrs but it didn't work.

[Wuffer]

More likely water valve.

[zebber500]

My car doesn't have the water valves, the previous owner removed them for some reason along with the aux water pump. I have had the car for 2 years and the air cond has worked good up until 3-4 weeks ago.This just started after my batteries went down.

[Shockleysprings]

Taylor, did the grab washer work? I've got the same problem.

[taylorpatterson]

Taylor, did the grab washer work? I've got the same problem.

No, since that time I removed the dashboard and discovered a broken driver side flap. Repaired that and life was good. It's unfortunate I had to go to the trouble but it's not impossible to do, just need to do a lot of research, find some confidence and take your time.

[Shockleysprings]

Figures, I couldn't get the bloody thing on there. Too old for this. Maybe it'll hold for a while. I think the drivers side has the same issue.

[killian665]

This sucks because mine is doing similar things but rather instead of it blowing hot or cold from where it’s not supposed to, my center vents work when they want. Usually they blow no air then after a time a loud think is heard in the dash and they start blowing air