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  Oct. 28, 2011 8:08 a.m. 16vCorey SuperDork

  A friend of mine bought a '97 328i about 6 months ago. I was meticulously maintained by the leading euro/performance shop in town, and came with a stack of service receipts, including a recently new radiator and water pump. Anyway, he just emailed me last night because he's having a strange problem. This is quoted from his email.

  Joe said: when the heat is on auto, its fine, but warm air only comes out of the floor and windshield vents (not the middle console vent, which only blows cold). if I have the heat on (temp set to like 80 degrees or so) but not on "auto" and i am driving, it is fine. if i have it set this way and am idling, the car will overheat within a few minutes. its almost like the mechanism that directs the hot air from the engine through the dash vent wont open so the heat backs up causes the overheating...??? anyway, its not an issue, as long as i keep it on 'auto' and am mindful when idling, its fine.

  Anyone else ever have this problem? Blend door actuators? Even if it is a blend door problem, that doesn't really explain the overheating. Weird.
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  Oct. 28, 2011 8:12 a.m. nderwater SuperDork

  Treat the real issue first - sounds like he needs a new fan clutch. In the mean time he should check his coolant level and keep a close eye on the temp gauge while driving.

  Auto photo blog: http://motomania.tumblr.com

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  Oct. 28, 2011 8:26 a.m. 16vCorey SuperDork

  If that's the case, why would it only overheat if the heat was on full blast and not when it's on "auto"?

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  Oct. 28, 2011 8:38 a.m. AngryCorvair SuperDork

  does the "auto" climate control setting also turn on the cooling fan(s) on the radiator? because it sounds to me like there's no airflow over the rad (assuming that "idling" means "car is not moving") when the climate control is not in the "auto" setting.

  if you're gonna be a bear.... be a grizzly bear!

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  Oct. 28, 2011 9:12 a.m. Strike_Zero HalfDork

  Fan clutch, coolant level, burp the system, check the dial on the dash to make sure it's turned to red and not blue . . .

  -=PJ=- "Curses . . . Foiled again!" - - - http://www.strikezerogarage.com

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  Oct. 28, 2011 9:18 a.m. 16vCorey SuperDork

  That thought had actually just occurred to me. If the "auto" setting sends heat out of the defrost vents (like he said in the email) than it may also engage the ac compressor (since a lot of vehicles use the ac compressor to remove humidity when in the defrost setting). And if it's doing that, then it's probably kicking on the condenser fan as well. Hmmm...Good call. I'll have to check that out.

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  Oct. 28, 2011 10:05 a.m. MadScientistMatt SuperDork

  AngryCorvair wrote: does the "auto" climate control setting also turn on the cooling fan(s) on the radiator? because it sounds to me like there's no airflow over the rad (assuming that "idling" means "car is not moving") when the climate control is not in the "auto" setting.

  E36s use a clutch fan; there's also an electric condensor fan that comes on with the AC. I'm wondering about the condition of the clutch fan.

  Also make sure the previous owner hasn't removed the clutch fan and left nothing in its place! For some reason, this is a popular mod in the E36 community as apparently you can get away with it if you don't idle for too long.

  "Mad Scientist" Matt Cramer

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  Oct. 28, 2011 11:38 a.m. Joe Gearin Associate Publisher

  16vCorey wrote: That thought had actually just occurred to me. If the "auto" setting sends heat out of the defrost vents (like he said in the email) than it may also engage the ac compressor (since a lot of vehicles use the ac compressor to remove humidity when in the defrost setting). And if it's doing that, then it's probably kicking on the condenser fan as well. Hmmm...Good call. I'll have to check that out.

  In the Auto setting the A/C is engaged unless it is switched off manually.(a/c button) I'm pretty sure the A/C will always run in the Auto setting regardless of what the temp setting is.

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  Oct. 28, 2011 11:53 a.m. JThw8 SuperDork

  yep, 2 different issues.

  As everyone has said, sounds like the clutch fan is toast, that's the main issue.

  Heat out of the center vents is minor, it has been alluded to but not spelled out for the non E36 savvy. There is a control wheel under the vents that is red at one end and blue at the other. Turn the wheel from blue to red, this controls whether or not heat or cool air will come out of the center vents.

  

  Its the wheel on the left in this photo.

  OTTER: "I think that this situation absolutely requires a really futile and stupid gesture be done on somebody's part." BLUTO: "We're just the guys to do it."

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  Oct. 28, 2011 2:56 p.m. mad_machine SuperDork

  if the auto setting is running the aircon, that means that the condenser in front of the radiator is heating up as it removes heat from the system. The car should compensate for this by turning on the aux fan that is infront of the condenser.

  Have your friend check to make sure that fan is working

  Be careful of your words, for someone will agree with them. Be careful of your conduct, for someone will imitate it. -Leih Tsu

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