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Subject: HVAC pushbutton repair follwup: How to fix buttons that won't stick Author: DavidC (moderator) : member since December, 2003 : 11918 posts Posted on: 2004-04-17 06:13:18

You may recall my earlier post about swapping the HVAC rotary dials with a working donor. Well, the pushbuttons which I thought were ok gave up the ghost this week, so I decided to document and photograph Kevin's excellent instructions on how to fix the HVAC pushbuttons.

If the pushbuttons for your HVAC control panel won't stay in, this is what you've been waiting for and it will save you a whopping $300 over the cost of a new pushbutton panel from a dealer. I've seen several pages on the internet describing the repair process, but none of them had photos.

The process will require about 30 minutes of your time. You'll need a small flat-blade screwdriver and a small philips-head screwdriver.


Assuming you've already removed the pushbutton panel from your dashboard, it will look like this on your workbench.



Remove the two philips screws on each end of the assembly.


Lift off the upper half of the assembly that contains the rotary wheel switches.


Using a small flat-blade screwdriver, remove the 7 screws on the circuit board that covers the pushbuttons.


Carefully remove the circuit board. The pushbuttons beneath it each have one spring and there's another spring in the orange plastic piece beneath the buttons. Don't let them fly out. Also, carefully note the location and labels of the two outer pushbuttons (recirculate and defrost) -- you'll want to make sure you put them back in the right locations when reassembling the unit.


A view of the pushbuttons after the circuit board has been removed.


Carefully lift each pushbutton out of the assembly and set them aside in the order that you remove them.


A closeup of the underside of a pushbutton, showing the spring it contains. This spring is what provides the resistance when you depress the button. Sometimes these springs break. As Kevin mentioned in his writeup, you can fashion a replacement by cutting the spring from a ballpoint pen to the proper length. When reinstalling the pushbutton, it helps to use a flat-blade screwdriver to lift the inner end (the end on the orange side) of the spring so that its out of the channel. This makes it easier to insert the end of the spring into the mating black plastic notch in the housing. Note the upper end of the orange piece with the two ridges. These ridges press against the white rubber cord when the buttons are in the inactive "out" position (next image).


A view of the housing with all of the pushbuttons removed. Note how the orange slide mechanism contains a spring between the 3rd and 4th (from the left) button positions. Note also the white rubber cord with the indentations. This is what we're going to repair.


A closeup of the white rubber cord. The cord provides tension against two plastic tabs (the upper part of the orange piece pictured earlier) of the pushbutton when it is in the 'out' position. The indentations in the cord are the problem, so we're going to slide the cord over a bit to let fresh portions of it line up with the ridges on the pushbuttons.


A view of the assembly with the orange slide mechanism (and its spring -- don't lose it) removed. Note the orientation of the orange slide mechanism before removing it.


Gently remove the white rubber cord.


Use a pair of scissors to cut away a small portion of the right side of the cord. Between the 1st and 2nd indentations, from the right side, is a good place to cut.


Reinstall the cord into the assembly so that fresh cord lines up in front of the slots. Reinstall the orange slide mechanism and spring.


Now for the tricky part. Reinstall each of the pushbuttons, taking care to ensure that each spring is properly fitted to the black plastic post beneath each button. As each button is installed, push it ever so slightly so that it is in the 'out' position.


A view of the rear of assembly with all of the pushbuttons installed.


Reinstall the circuit board to cover the pushbuttons. I found it best to insert the two rear screws first, but not to tighten them. Then you can lay down the circuit board onto the pushbuttons so that the metal guides on the bottom of the circuit board line up with the contact points for each pushbutton. When you've got them all lined up and working, go ahead and insert the remaining five screws into the circuit board.

Reinstall the rotary wheel switch assembly and you're done!

David Cecil
'97 740iL, 119k miles
'86 735i, 91k miles
'77 320i, 140k miles

www.e38.org has links for everything about your BMW 7-series automobile

• HVAC pushbutton repair follwup: How to fix buttons that won't stick (pic) (url) - DavidC 2004-04-17 06:13:18 (7759 views)
  • And here's how to replace the microswitch for the fan speed wheel, too (url) - DavidC 2004-04-27 22:31:56 (955 views)
  • Nice pics...don't wait to do this repair everyone - Kevin '86 735i VA 2004-04-19 00:54:16 (717 views)
  • Awesome repair posts! - comptech 2004-04-18 00:57:09 (572 views)