what just happened...?

[Luftwaffe1O1]

Went to switch my temp knob from cold to hot, there was a lot of resistance at about 1/3 of the way over, there was a cracking sound almost and now the knob moves with ease.

For a few weeks now, there was a lot of resistance when moving the knob from cold to hot a clunk could be heard when switching, and the car had trouble blowing hot air...

Now however, hot air blows just fine, and it blows colder air when switched back to cold... Did I potentially break something?

[kieskaman]

sounds like its working fine now. I hope it was just
sticking? Lots of plastic in there

[yash]

These require tender touch and gentle coaxing due to very brittle plastic which snaps faster than Huessain Bolt.....had to repair mine already.....and trust it was a pita.

[SamGrant951]

Mine did the same thing recently - not getting really hot heat out of this coupe either, havent investigated yet...annoying.

[jersey2.8]

These require tender touch and gentle coaxing due to very brittle plastic which snaps faster than Huessain Bolt.....had to repair mine already.....and trust it was a pita.

How to fix?

[dkindig]

There is an arm on the back side of the heat control that controls the cable to the heater blend door. This arm has a round molded pin that rides in a nautilus-shaped track on the heat control and the pin has broken off of the arm.

To repair, pull your radio, remove the two screws visible on each side of the console just underneath the radio, pop the heater control assembly out (toward the front of the car) and you should be able to flip it up and see the arms I'm talking about. They snap over a post and should just pop off of it.

Once you get the arm for the heat control off (should be the second one in the stack), you will see where the ball snapped off. Go online and get a metal bellcrank ball with a 4-40 thread from a hobby supply place. These are used on radio-control cars and airplanes. Use the proper-sized drill bit and drill a hole right where you see the original ball broken off, tap for 4-40 threads and thread the metal ball in using blue threadlocker.

Reassemble and you're done! The root cause is the disintegration of a foam seal on the heater blend door that causes it to stick in place. That is a whole different level in terms of a fix, but replacing the ball with a more durable substitute works without digging into all of that...

[Jeremy]

My bet is the sliding channel on the back of the knob broke, or the pin that slides in it did. I've seen this posted many times. I'm on my phone now, but will post a link the next time I'm on my laptop.

[yash]

How to fix?

There is a DIY somewhere. But you basically have to remove your radio and work through that hole....and be prepared to endure pain as it is a little tedious to twist around the ac controller to remove the cables while your hand is getting butchered .

[jersey2.8]

There is an arm on the back side of the heat control that controls the cable to the heater blend door. This arm has a round molded pin that rides in a nautilus-shaped track on the heat control and the pin has broken off of the arm.

To repair, pull your radio, remove the two screws visible on each side of the console just underneath the radio, pop the heater control assembly out (toward the front of the car) and you should be able to flip it up and see the arms I'm talking about. They snap over a post and should just pop off of it.

Once you get the arm for the heat control off (should be the second one in the stack), you will see where the ball snapped off. Go online and get a metal bellcrank ball with a 4-40 thread from a hobby supply place. These are used on radio-control cars and airplanes. Use the proper-sized drill bit and drill a hole right where you see the original ball broken off, tap for 4-40 threads and thread the metal ball in using blue threadlocker.

Reassemble and you're done! The root cause is the disintegration of a foam seal on the heater blend door that causes it to stick in place. That is a whole different level in terms of a fix, but replacing the ball with a more durable substitute works without digging into all of that...

Thanks! I'm putting this on the to do list...

[bimmerbri2]

Here is a picture of the arms...I used a rivet to fix it. Lots of DIY articles and search is your friend.

[dougmcintyre]

http://www.bimmerfest.com/forums/sho...highlight=HVAC and http://www.bimmerfest.com/forums/sho...highlight=hvac are both useful links. Yea, the first starts out with replacing the HVAC bulb, but evolves to repair issues.

[Luftwaffe1O1]

Perhaps I wasnt completely clear in the original post, it seems that after the "cracking" sound, my air system seems to be working normally again.

Prior to this, there was a clunk when I would try to switch to hot air, and the car would never quite heat up properly. Now, it heats up just fine (I was thinking the thermostat was bad). It also cools blows cool air no problem. If something broke, would there be any symptoms? Like I wouldnt be able to switch between heat and cold?

[dougmcintyre]

As jersey2.8 said, "The root cause is the disintegration of a foam seal on the heater blend door ". When the foam rots away, you are left with two sided sticky tape.

I'd guess the clunk was caused by the heater blend door suddenly moving and stopping after being released from the sticky tape. And the cracking sound was the tape being ripped off the door "frame".

[mpire]

Yeah, pretty much.

Here is a video.

http://www.youtube.com/watch?feature...&v=sVAqk0kz5qU

[BiloxiGuy]

Another good link, and what I used to fix mine.

http://www.bimmerfest.com/forums/sho...5&postcount=11

[bzaster]

This same thing happened to me. Now I pretty much only have full hot, or full cold (doesn't bother me much).

When the knob feels like it has tension, I ease it back and forth slowly and it gradually gets to hot. I don't want to hear that cracking noise ever again.

[QuestMCoupe]

Same thing happened to me and I ended up breaking the piece on the HVAC controller

I have another unit to replace it with, but I've been lazy to get out there and replace it.

[satbeachbill]

Same thing happened to mine. Knob is broken off on the controller. Everyone said start with removing the radio. Yeah, right. I can't seem to locate ANY screws to remove the thing. So I can't get past square one. The console and up past the radio and knobs are all covered by a brushed aluminum trim plate. No screws or clips. Now what?

[wrench13]

If you have the BMW Business radio, there are two little rectangular plastic panels on either side of the radio. Gently pull them up, from the inner edge - you'll see two screws that are hard to get to, but remove them and the radio comes out.

[satbeachbill]

I don't know the model radio, I'll take a look tonite. Thanks

[TopDownRoadster]

Any help would be appreciated! Thanks!
I had a similar issue....my knob was the same,tough to switch from Cold to hot but I would manage to get it turned and had cold and hot air blowing. Then the last time I really forced it from cold to hot b/c it just wouldn't budge and I must have broken it. Now it is very loose and so easy to turn but I have no hot air at all... I still have cold . Anybody know what I must have done wrong and how to fix it? I am not really the fix it type at all but I may have a willing friend that wants to help out.

[dkindig]

Any help would be appreciated! Thanks!
I had a similar issue....my knob was the same,tough to switch from Cold to hot but I would manage to get it turned and had cold and hot air blowing. Then the last time I really forced it from cold to hot b/c it just wouldn't budge and I must have broken it. Now it is very loose and so easy to turn but I have no hot air at all... I still have cold . Anybody know what I must have done wrong and how to fix it? I am not really the fix it type at all but I may have a willing friend that wants to help out.

Tell you what...

I just responded to your other thread on the rear window. In exchange for the rear window, I will send you a replacement thread-in ball for your heat lever and help you/your friend get walked through the fix...

[satbeachbill]

Thanks for all the help. I fixed the temp control yesterday. I removed the radio and control arm. I screwed in a ball link and it works fine. Thanks very much for all the tips. While I was at it, I removed the glovebox and brackets and adjusted the cable for the blender door. It sure works smooth now!

I have a couple extra ball links if anybody needs one.

[Z3speed4me]

Sorry to bump... but;

Would this be similar to my issue of hot air only blowing on 3&4 but getting cold air on 1&2 regardless of how high the heat is spun to the right?

[resunoiz]

mine does that always when is too cold turning anti-clockwise
I learned to turn it clockwise when temp is cold