Next installment ready. This is about stripping the final bit of the unit and cleaning everything up properly.
If you've followed the previous steps, you will now sit with the climate control unit separated into the following bits and pices.
1: The removed backlights.
2: Back cover.
3: Main circuit board.
4: Face plate circuit board.
5: Face plate - complete with buttons.
The back of the face plate has two clear plastic light diffusers and the back end of the buttons and looks as below. The light diffusers can be removed simply by pulling them straight backwards. Once this is done, note the orientation of the button guides / inners inside face plate.
Two of these buttons are important as they are the ones that tend to stick. I'll get back to them shortly.
Each button consists of two parts - the outer button (which we see from the front of the unit) and the guide / inner - which is the white plastic thing we see from the back. To remove the buttons is finicky. But before doing so, make a note of which button goes where so that one puts them back in the correct space again at assembly time.
To remove the buttons, press the button from the rear side of the unit forward as far as it will go. Insert a small flat screwdriver underneath the bottom of button (ie: bottom being the bottom of the unit) at the front and gently pry it up. Gently - you do not want to break it. This will release the clip of the button face. The face of the button comes out from the front. Press the white plastic guide bit out towards the back.
The result of this is that the unit will not be completely disassembled.
At this point, we clean everything up. I used normal washing detergent and an old tooth brush to scrub everything clean. Especially the congealed "plastic" lubricant on the button guides.
Stuck Buttons
There are two buttons that seem to get stuck on these units - namely the recirculate and non-recirculate buttons on the top left of the unit. There are several reasons for this - the lubricant congealing with age being one of them. However, inspection of the buttons and the guides show another reason as well.
Unlike every other button on the board, these two buttons are the only buttons where the switch it presses on the circuit board is not towards the middle of the unit. As such, pressing the buttons will always result in the button inner pulling a little skew in it's guides. The points where the buttons connect with the actual switches on the circuit board are highlighted below.
What happens over time is that the inner button guide ribs wear a spot into the cover's guide slots. This means that, when the button is pressed, the guide rib catches in the guide slot and it gets stuck. Using a dremel or a craft knife, carefull cut the guide ribs highlighted below so that they taper towards the back, making sure that the new, cut surface is nice and smooth.
After cleaning everything, use a very slghtly damp piece of kitchen towel to clear the inside the the LCD display on the front cover. At this point, we can start reassembling the face plate. Using a bit of proper plastic lubricant (I used the lubricant they use for plastic runners on garage doors), lubricate the button inners. Not too much - just a smidgen. From there, we reinstall the button guides from the back of the face plate in the same orientation as we noted when disassembling the unit. Place the front of the button over the button guide from the front (in the correct place, naturally) and apply a bit of pressure. The button face will click onto the button guide. At this point, we must remember to put the light diffusers back. They have guides they fit onto, so one can only put them back on in the correct orientation. This done, we can now put the face plate circuit board back on - gently pressing it into the tabs which hold it in place at the top and the bottom edges of the face plate. And we can put the three screws back. Our face plate should now be clean and have working buttons.
The next instalment will be up when I have time. This will deal with removing and cleaning the LCD backlight assembly. After that, I'll get around to getting the lights to work.
