GO FISHING, use SLABSAUCE Fishing Attractant
Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: 1990 525i - Confusing climate controls!

  1. #1
    Join Date
    Jan 2006
    Location
    St Louis, MO
    Posts
    44

    Default 1990 525i - Confusing climate controls!

    I'm a bit baffled by the climate controls in my M20 E34 (wow, learning the lingo already). Here's what it looks like:



    Sometimes, when I turn both knobs to full heat, the two vents in the center won't blow the same air. One will blow hot and one will blow cool. Does this have anything to do with the red-blue slider between the two vents? I dont understand what it does.

    Also, on the blower, what is the fan speed before "1" supposed to do? It seems to be on, but blowing very gently at the same speed no matter where I set it. Could buildup behind my evaporator be preventing the fan from blowing more air?

    Thank you!
    -Jesda
    1990 Infiniti Q45 - http://www.Q45.org/
    1990 BMW 525i - Sold

    Creve Coeur, MO

  2. #2
    Join Date
    Oct 2004
    Posts
    3,395

    Default

    Well, the real problem is that you keep on thinking about that totally useless excuse for an automobile known as the Q45

    Most non microfiltered/early E34s have a mouse nest or two in the heater box (the theory here is that ones with microfilters get cleaned more often than not) which can stink up the air (egh!) and minimize air thoroughput. So, check for "backup behind [sic: actually, in front of] the evaporator."

    The heat discrepancy could be a sticking heater valve, flap issue (unlikely) or potentiometer issue in the vent temp wheel (also unlikely since that pot regulates both sides). Searching "heater valve" will return myriad results, so do that first.


    best, whit

  3. #3
    Join Date
    Dec 2003
    Location
    baton rouge, loserana
    Posts
    6,922

    Default

    the roller between the vents changes the mix of air coming through the vents in the dash, say your feet are cold but you don't want to roast your hands/face but still want airflow you turn the heat up and that roller between the vents to blue, air through the vents too cold but floor is good crank in a little more red, it's varly sensitive so you can adjust it to a good degree of comfort
    all america wants is cold beer warm cat and a place to take a poop with a door on it

  4. #4
    Join Date
    Mar 2005
    Location
    Hockinson, Washington
    Posts
    2,499

    Default

    How does one go about checking for mouse nests? My fan is very weak and makes a noise deep throbbing noise when turned to full power, like that of a criuse liner's deisel engine. At three, the noise is not so prominent but the airflow is weak. Anything below three is useless. On an e28, the blower fan is where the expansion tank is on my car...
    Lowered with blue h&r(?) springs, Bilsteins, tint, 19# design 3 injectors, Dual Magnaflow
    southwest WA

  5. #5
    Join Date
    Jan 2004
    Location
    Atlanta
    Posts
    206

    Default

    Quote Originally Posted by Alexlind123
    How does one go about checking for mouse nests? My fan is very weak and makes a noise deep throbbing noise when turned to full power, like that of a criuse liner's deisel engine. At three, the noise is not so prominent but the airflow is weak. Anything below three is useless. On an e28, the blower fan is where the expansion tank is on my car...
    Change your microfilter for the weak airflow. As for the grinding/throbing sound, wait it out. It may be that when you change the filter it goes away, but if it does not a new motor may be in your future. This should be a long time in the future. Mine made racket for years before finally giving up. Quite a simple process and only about 200 bucks.

  6. #6
    Join Date
    Jan 2006
    Location
    St Louis, MO
    Posts
    44

    Default

    Quote Originally Posted by lowell
    Well, the real problem is that you keep on thinking about that totally useless excuse for an automobile known as the Q45
    Only I get to badmouth my ex lovers! =)

    Thanks for the help guys.
    1990 Infiniti Q45 - http://www.Q45.org/
    1990 BMW 525i - Sold

    Creve Coeur, MO

  7. #7
    Join Date
    Mar 2005
    Location
    Hockinson, Washington
    Posts
    2,499

    Default

    Quote Originally Posted by tdgard
    Change your microfilter for the weak airflow. As for the grinding/throbing sound, wait it out. It may be that when you change the filter it goes away, but if it does not a new motor may be in your future. This should be a long time in the future. Mine made racket for years before finally giving up. Quite a simple process and only about 200 bucks.
    ONLY $200? I pretty sure i dont have a microfilter.
    Lowered with blue h&r(?) springs, Bilsteins, tint, 19# design 3 injectors, Dual Magnaflow
    southwest WA

  8. #8
    Join Date
    Feb 2004
    Location
    Minnesota
    Posts
    499

    Default

    1990 E34's don't have a microfilter, also, the HVAC system is a bit different as the older E34's have a "sword" final stage resistor that works to adjust the fan speed when you set the dial. Despite the fan number settings and the corresponding detente's, this is a continously variable fan speed. If you set the fan switch between two detente's, it will blow at a speed between the two numbers...Do a search on the topic and you'll find more info. also visit Bruno's site on this as well. Low airflow could be clogged heater core area on the non-microfilter cars, or, possible problem with the "sword". If you remove the sword you can kinda see whether the heater box area is clogged. Sword is on passenger side and tricky to get at (see Bruno's site). If air is cold on one side and warm on the other and your dials are set the same, check the water valve operation, located on driver's side under the hood near the firewall. You'll see two hoses coming out and going into the firewall for the heater core. Good write-up on that in Bruno's site as well.

  9. #9
    Join Date
    Jan 2006
    Location
    Austin Tx.
    Posts
    7

    Default

    what year did the microfilter's get put in?

  10. #10
    Join Date
    Jan 2006
    Location
    St Louis, MO
    Posts
    44

    Default

    Thanks Jon! I notice on mine, it blows cold until I switch off the floor and turn on the center vents. Very odd. But after that if I turn off the center vents and go back to the floor, it continues blowing hot air as intended.

    When you refer to a clogged heater core area, youre talking about the area outside of it where things can build up, not the inside of it due to buildup of acidic coolant, right?
    1990 Infiniti Q45 - http://www.Q45.org/
    1990 BMW 525i - Sold

    Creve Coeur, MO

Page 1 of 2 12 LastLast

Similar Threads

  1. climate controls
    By ///Sniper535 in forum 5 Series BMW
    Replies: 2
    Last Post: 09-09-2008, 10:57 PM
  2. Replies: 1
    Last Post: 05-02-2008, 05:32 PM
  3. Replies: 5
    Last Post: 10-07-2006, 09:07 PM
  4. 525I climate control problem
    By Conecaster in forum 5 Series BMW
    Replies: 1
    Last Post: 06-09-2006, 03:53 AM
  5. where do I get lights for OBC and climate controls
    By Unregistered in forum 5 Series BMW
    Replies: 2
    Last Post: 03-18-2004, 10:26 AM

Posting Permissions

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