Heater temp knob adjustment?

[reelizmpro]

You only need to pull the climate control panel to access the bowden cables. In fact, you can inspect them from the glove box area if you remove the panel or from underneath if you remove the center console. Again, if the cable is not secured, then the lever is pulling/pushing the entire cable/sleeve instead of just the cable inside the sleeve. I removed them when I did my first swap and had a hell of a time getting everything back in the right place with the right adjustments. From then on, I leave the climate control cables intact. Not E30 but same principle...





The air mix cable runs along the bottom of the temp knob and there's a metal clip that secures it to the frame.

[Das Delfin]

Give this a read. Page 28 of the owner's manual

[jeffnhiscars]

Again.....what temperature sensor ?

[rmdashrf]

That's an interesting find in the manual. You can see the evolution of that same concept in the E46, but there, they give you another knob that allows you to do anything you want apart from the regular HVAC controls.

Sent from my LG-H918 using Tapatalk

[Das Delfin]

Again.....what temperature sensor ?

I mean the main part of what I was saying was the paragraph in the lower left of the picture. But I did a few google searches and a check on realoem and found this

http://www.realoem.com/bmw/enUS/showparts?id=BB13-USA-06-1987-E30-BMW-325i&diagId=64_0514

#18 at the bottom reads "repair kit temp sensor." 64111394105

And no, it isn't the evaporator temp sensor ;)

Here is a side view of the A/C evaporator/heater core/blower motor assembly taken from the Bentley manual. As you can see there is a flap between the heater core and evaporator that as you turn the temp knob towards hot, rotates up (this is what's connected tot he bowden cable on your temp control). You can see how it allows some cool air to directly bypass the heater core, which is then routed up to the mid level vents. The diagram shows the air traveling through the heater core and the bypassed air flowing to the same duct but I believe there is a separation not shown within the scope of this diagram.



The manual says the floor vents need to be at least halfway open for the temp sensor to get an accurate reading. I'm guessing bmw put the temp sensor in question in the heater box rather than next to the temp control because I've looked down my vent and found nothing.

But anyway that's the answer to your question. But.. you don't have to believe me. This is all taken from bmw documents that seem to line up with how I've experienced my car behaving. Which is very different from other makes I've owned.

The e36 expanded on this by adding a temp control between the two middle dash vents that lets you add warm air to the mix independent from what's going on elsewhere in the hvac system.

[Das Delfin]

Side note, I found a pdf version of the owners manual and the bentley manual from searching around online. I think I got one from r3v and one from bimmerforums. But use google and you'll find them. They were free and are (somewhat) searchable

[Dave_G]

The temperature dial has very little resistance but it feels the same throughout the whole range. I definitely get warmer air out of the defrost vents than I do out of the face vents. I guess I'm going to chalk this up to normal e30 behavior even though I don't remember it being like that before.

Mine has always done exactly the same thing as yours. My old E30 did that, and someone told me it was caused by a bad heater control valve. So I replaced the heater control valve, and it still did the same thing. My current E30 acts exactly the same as you describe, kind of like:

cold cold cold cold cold cold cold cold cold cold cold cold cold hot
<0-----------------------------------------50------------------------------------------100>

So from my limited experience, that's just how they work.

I haven't checked the difference between the three outlets, but I'm going to soon. That they would be different is kind of intriguing.

[jeffnhiscars]

I put my VIN in to realoem and I don't have that part on my 87 cabrio

[Das Delfin]

I don't know what you want me to say. I found that diagram using info from my 6/87 cabrio

[Dave_G]

IBut.. you don't have to believe me. This is all taken from bmw documents that seem to line up with how I've experienced my car behaving. Which is very different from other makes I've owned.

Wow. I've owned E30s for 10 years, so how come it has taken me this long to learn how to work the heater in the car?

Today I had a long drive in cold weather, and I tested it out -- Das Delfin is 100% correct. When the temperature knob is turned to full warm, warm air comes out all three outlets: defrost, dash vent, and floor. But when you turn the temperature knob down even a little (such as when your shoes start melting), the dash vents go full cold, but the defrost and floor vents get less warm, following the position of the knob.

IOW, the dash vents have only two settings: full hot or full cold. The defrost and floor vents are adjustable. The solution to comfortable winter driving is to turn off the dash vents after the car has warmed up.

I can't believe it took me 10 years to learn this! :p

[reelizmpro]

Wow. I've owned E30s for 10 years, so how come it has taken me this long to learn how to work the heater in the car?

Today I had a long drive in cold weather, and I tested it out -- Das Delfin is 100% correct. When the temperature knob is turned to full warm, warm air comes out all three outlets: defrost, dash vent, and floor. But when you turn the temperature knob down even a little (such as when your shoes start melting), the dash vents go full cold, but the defrost and floor vents get less warm, following the position of the knob.

IOW, the dash vents have only two settings: full hot or full cold. The defrost and floor vents are adjustable. The solution to comfortable winter driving is to turn off the dash vents after the car has warmed up.

I can't believe it took me 10 years to learn this! :p

That has not been my experience and I've owned E30's practically since new. I only use the center dash vents on my cars and I can get any temp I want in between full cold and full hot. I won't post the same stuff over and over but it sounds to me like you guys have the same issue.
EDIT: just read that this may be because I typically only use the center and top vents and never noticed what you guys are experiencing. Will try it tonight.

[Dave_G]

I only use the center dash vents on my cars and I can get any temp I want in between full cold and full hot. I won't post the same stuff over and over but it sounds to me like you guys have the same issue.
EDIT: just read that this may be because I typically only use the center vents and never noticed what you guys are experiencing. Will try it tonight.

Interesting. I'll add that both of my E30s have acted the same way, so unless they were broken in the same way, it seems more like a BMW design feature. I just read the owner's manual, and while it's slightly different from Das Delfin's example, it does say what amounts to the same thing when describing the center dash vents:

If the footwells are supplied with heated air at the same time, warmer air reaches the footwells according to the setting of rotary temperature control 1, and blends with the cooler air to provide a pleasant, stratified temperature pattern inside the car, e.g. to allow cooler air to be directed at the driver's head to help reduce fatigue.

So, warm air on your feet, cool air on your face, which is exactly what my car does. I'd guess it may be most noticeable in winter weather with sub-freezing outside temperatures.

[reelizmpro]

Right, I may not have even noticed because I typically don't use the top/bottom vents unless needed and apparently that's the key. Completely closing the other vents makes the center vent stronger and that's more important to me in a warmer climate. Even when it's cold, I only typically use the center and maybe the top vents. I don't care if my feet/legs are warm/cold lol.

[Dave_G]

Right, I may not have even noticed because I typically don't use the top/bottom vents unless needed and apparently that's the key. Completely closing the other vents makes the center vent stronger and that's more important to me in a warmer climate.

Ah, maybe that's the difference. I just found this bit in the manual:

The lower air distribution lever should always be left at least half open so that the temperature sensor can operate.

If I thought hard enough about it, maybe I could come up with an explanation why closing the lower vents could confuse the system enough to send warm air out through the dash vents. :)

[Das Delfin]

If I thought hard enough about it, maybe I could come up with an explanation why closing the lower vents could confuse the system enough to send warm air out through the dash vents. :)

Came across this. Finally just googled "how does a e30 heater control work"

http://www.e30zone.net/e30zonewiki/images/3/3d/E30_heating.PDF

I haven't read it yet but it looks official so if it contradicts what I'm saying so be it!

edit... that's your answer.

Where does the temp sensor come into play? My guess is that if you have an electronic heater control valve a temp sensor is just one step away from an automatic thermostat.