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735owner 
Newbie 
Joined: 14-November-2005 Status: Offline Points: 26 |
 Topic: Fan blows on cold but switches off on hotPosted: 28-November-2005 at 05:51 |
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BMW 735 (E32) Hi, I've got a problem with the heater fans , Everything works fine if I want cold air but if I increase the heat on the temperature dial control the fans stop blowing. Not the ideal weather for a heaterless car. Any ideas ? Thanks |
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shogun
Really Senior Member II 
Joined: 22-February-2005 Location: Tokyo/Japan Status: Offline Points: 564 |
Posted: 28-November-2005 at 21:21 |
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The fan speed is controlled by the socalled sword. That is a common problem that this has to be resoldered. http://www.bmwe34.net/e34main/maintenance/electrical/sword.h tm Another problem could be the IHKA control module which sits behind the sword. Also here same procedure. Open it up, look for bad solderings. |
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735owner
Newbie
Joined: 14-November-2005 Status: Offline Points: 26 |
Posted: 29-November-2005 at 12:07 |
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Thanks Shogun. Are there 2 fans ? I.E. one for HOT and one for COLD ? I ask this because I get cold air in all vents perfectly ( variable speeds using the control ) so that indicates ( to my uninformed brain ) the fan and resistors are fine, but as I increase the temperature dial the air flow decreases until it has to heat the air above ambient temerature at which point it stops totally. It although the sensor which tells the computer how hot the car is, Is telling the computer the car is hot enough and no more hot air is required, Causing it to shut off the fan(s). Or that the routing/sourcing of hot air is blocked. Or am I barking up the wrong tree and its caused by a faulty resistor as you imply.
Many thanks for your thoughts and input.
Edited by 735owner |
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rubberknees50
Really Senior Member II
Does it have chrome bumpers? Joined: 26-July-2004 Location: Telford, Shropshire Status: Offline Points: 1074 |
Posted: 29-November-2005 at 13:06 |
Is this the same as for the E23, as my old 732, now with new ownerm has fan blows fuse over 1.5 speed but works fine on defrost. Told this is the resistor pack (box of springs) but no idea where to look for old one to change it and loads to do on my replacement 735. Posted question but got no response. Told it's a common problem so someone must know. |
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IanT
E28 528, E23 735 
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735owner
Newbie
Joined: 14-November-2005 Status: Offline Points: 26 |
Posted: 12-December-2005 at 13:53 |
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I drove on sunday evening and the near zero temperatures caused Ice on my windscreen, lots of misting up and very cold fingers, so I have resolved to fix the lack of heater and not just ignore the problem as I have been doing. Having a look thjrough the RealOEM parts catalog I have discovered that there are indeed two fan motors, One for the Aircon and one for the heater. ( http://www.realoem.com/bmw/partgrp.do?model=GB42& mospid=47344&hg=64&fg=40 ) Does anyone know how one gains access to the heater motor or where abouts its located ?
Many many thanks in advance for any useful pointers. Edited by 735owner |
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rubberknees50
Really Senior Member II
Does it have chrome bumpers? Joined: 26-July-2004 Location: Telford, Shropshire Status: Offline Points: 1074 |
Posted: 13-December-2005 at 07:31 |
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Ok, the two blower motors on mine are in front of the windscreen by the bulkhead, under the wiper linkages. Got to take mine apart to invetigate lack of response! |
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IanT
E28 528, E23 735
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Fan blows on cold but switches off on hot
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shogun wrote: