Results 1 to 10 of 10

Thread: 91 Soft Top rear window defroster heating element?

  1. #1
    Join Date
    Jul 2017
    Location
    Columbia, SC
    Posts
    12
    My Cars
    2010 128i Vert

    91 Soft Top rear window defroster heating element?

    91 320i Cabrio, Euro spec.

    Need a bit of help, please.

    I've tried two blower units and both blow air, but it isn't hot at all. Looking into either unit at their heating coils, neither are heating up or glowing, indicated it ain't getting any current.

    Does the orange relay on the wiring harness control the current running through the heating coil? If so, that will be a pretty easy fix.

    I just find it hard to believe that I purchased a good condition blower that happens to have the same problem as the one my car came with.

    Thanks!

  2. #2
    richardodn's Avatar
    richardodn is offline Old Guy BMW CCA Member
    Moderator
    Join Date
    Nov 2008
    Location
    Lakewood, CO
    Posts
    9,942
    My Cars
    20 440ix cab, 12 X3 35ix
    I don't believe they actually have a heating element. My e36 does not.
    "Howdy, Folks!"

    1986 Delphin 528e - Roof rack equipped lumber hauler.
    1989 Zinnoberrot 325iX Sedan - I miss this car. (Deceased)
    1998 Avus Blau 328iC - Someone else's project now
    2008 Platinum-Beige X3 3.0si - Current project
    2012 Alpine White X3 xDrive35i - My new snowmobile.
    2020 Estoril Blue 440i xDrive cabrio - This car is a blast to drive.

  3. #3
    Join Date
    Apr 2010
    Location
    Athol, MA
    Posts
    458
    My Cars
    87 M6, 90 325iC, 89 iX
    I took the one in my former 1990 vert apart and it did have a heating element. I could even smell it when it heated up. Less so once I cleaned all the dust out of it.
    Attached Images Attached Images
    "Life is too Short to drive boring cars"


    1986 325E
    1989 325iX (Long term 5-speed/refresh project)
    1993 MB 300E
    1995 MB E320
    2000 Audi TT (Winter AWD snow beast)
    2007 Porsche Cayman S (Summer car)
    2009 VW Touareg

  4. #4
    Join Date
    Apr 2015
    Location
    Toronto
    Posts
    492
    My Cars
    e30s
    I believe what you smelled was the motor under strain as the motor heated up from the accumulation of dust; Dust is not a motor's friend or for any ellectronics.

    - - - Updated - - -

    I don't believe any of these units were designed to create heat. How it works is through the cabin temperature. As the cabin heats up it circulates the air and this defogs the rear plastic window.
    the hard tops had a rear window defrost element in it which was connected to the body of the car. Once the roof was put on the rear window defogger was no longer operational.

    I live in Canada and a good number of cabrios I had never had this.

  5. #5
    Join Date
    Apr 2010
    Location
    Athol, MA
    Posts
    458
    My Cars
    87 M6, 90 325iC, 89 iX
    I have since sold the car but I am almost certain that the "coil" riveted to the metal piece heated up. If the fan was to only circulate ambient air then this "assembly" would not even need to be inside the plastic housing.
    "Life is too Short to drive boring cars"


    1986 325E
    1989 325iX (Long term 5-speed/refresh project)
    1993 MB 300E
    1995 MB E320
    2000 Audi TT (Winter AWD snow beast)
    2007 Porsche Cayman S (Summer car)
    2009 VW Touareg

  6. #6
    Join Date
    Jul 2017
    Location
    Columbia, SC
    Posts
    12
    My Cars
    2010 128i Vert
    Quote Originally Posted by 1SGDHORN View Post
    I have since sold the car but I am almost certain that the "coil" riveted to the metal piece heated up. If the fan was to only circulate ambient air then this "assembly" would not even need to be inside the plastic housing.
    Nor would it be enclosed between the seatback and trunk. I’ll do a disassembly and test parts with a multimeter. Anyone else have insight?


    Sent from my iPhone using Tapatalk

  7. #7
    Join Date
    May 2015
    Location
    PDX USA
    Posts
    13
    My Cars
    ML350
    pretty sure mine heats up.
    1991 325i vert, white/tan, power black top, I bottlecaps. PDX

  8. #8
    Join Date
    Apr 2015
    Location
    Toronto
    Posts
    492
    My Cars
    e30s
    I did a little DD on this and apparently the rear blower fan does have heater coils in them. The picture shows two plugs. one for the relay and I would imagine the other is power to the heating coils.
    Something I had never known.

    Question: wonder if it can be repaired DIY?

  9. #9
    Join Date
    Jul 2017
    Location
    Columbia, SC
    Posts
    12
    My Cars
    2010 128i Vert
    Quote Originally Posted by Ceekers View Post
    I did a little DD on this and apparently the rear blower fan does have heater coils in them. The picture shows two plugs. one for the relay and I would imagine the other is power to the heating coils.
    Something I had never known.

    Question: wonder if it can be repaired DIY?
    Now we are talkin'. I'm gonna do some work on the car this weekend, so I'll test the connections.

  10. #10
    Join Date
    Nov 2009
    Location
    KANADA
    Posts
    221
    My Cars
    E3x2, E9, ixX2, ic, 02 +
    i know I’m late to the table but throwing this in here. IIRC there is a thermal fuse Inside it that blows.
    A

    Quote Originally Posted by bugleboy21 View Post
    91 320i Cabrio, Euro spec.

    Need a bit of help, please.

    I've tried two blower units and both blow air, but it isn't hot at all. Looking into either unit at their heating coils, neither are heating up or glowing, indicated it ain't getting any current.

    Does the orange relay on the wiring harness control the current running through the heating coil? If so, that will be a pretty easy fix.

    I just find it hard to believe that I purchased a good condition blower that happens to have the same problem as the one my car came with.

    Thanks!

Similar Threads

  1. Replies: 12
    Last Post: 09-19-2014, 07:05 PM
  2. Z3 E36/7 FS: NEW OEM Soft Top Rear Window Protection Cover (BMW # 54218410559)
    By kojohns in forum Z3,Z4,Z8 Classifieds
    Replies: 0
    Last Post: 02-13-2013, 12:43 PM
  3. Remove soft top rear window?
    By B328iC in forum Convertible Questions
    Replies: 3
    Last Post: 12-08-2012, 10:20 AM
  4. Soft top rear window plastic trim?
    By M5bill in forum Convertible Questions
    Replies: 8
    Last Post: 06-09-2008, 02:05 PM
  5. Slow rear window defroster?
    By Dwayne in forum 1988 - 1996 (E34)
    Replies: 3
    Last Post: 02-19-2004, 04:41 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •