My recirculation and defogger button on the right side of the CCU needed help. Although functioning, the icons were almost rubbed off, and the top recirculation button wasn't completely attached to the CCU and would pop off when I hit bumps. Porsche doesn't sell just the buttons, You need to buy the entire double switch. For my particular CCU, it was part number: 944-653-921-00.
Using radio removal tools, I slide the CCU out of the dash, gently pushing from behind. Leave a cloth underneath the CCU to protect the dash. Also watch out for the turn signal and cruise stalks when sliding the CCU out like a radio. There are two wire harnesses connected to the rear, they have a hinge and a snap on opposite sides of each connector. The layout of each plug is opposite the other plug with hinge and snap on opposite sides.
With the CCU free of the two wire harnesses, slide it out and bring it to your bench, or your knee.

 

While I was in here, I pulled off the air sampling fan at the rear, and blew out the cobwebs from the rubber tube that runs the length of the CCU. I unscrewed the two brass bolts, (top picture, 10 & 4 o'clock) dropped the fan unit off the CCU 'C" bracket and took the lid off the motor and cleaned and lubed the spindles. By the way, If the Scantool tells you code: '45 Inside temperature sensor fan', this is the fan that can get gunked up. It sucks in cabin air to measure the temperature. The nuts are held in place along the side of the plastic motor casing, but they can get loose and drop (4th picture).
The fan draws air from the long rubber tube (Last picture)

 

Meanwhile, back on the CCU, there are 6 black plastic tabs (3 on each side, 2 shown here, ovaled, which are pushed simultaneously to slide out the front. The only connections are the white ribbon cable connector (center-left) and the rubber tube for air sampling (far left) [Blue arrows]
Pry, then pull off the rotary control ***** and remove the 10mm nut under each rotary ****. (bottom)

 

The Front section that just slid off, splits into 3.
a black outer faceplate.
a clear plastic layer that holds the switches and
A green circuit board,
All are held in place with plastic clips. The switches snap into the clear plastic piece which snaps into the black faceplate. The green PCB 'plugs into' the switches and has the actual ***** and sliders.
After replacing the switch, slide the clear plastic lens back into the black plastic face, and slide the Print circuit board back onto the face. There are holes that line up on the PCB for the air volume sliders, rotary ***** and the switches on either side including the switch I just replaced. Make sure the PCB plugs in perfectly. ensuring all the holes and switch pins line up properly. The whole face now slides back in, also be careful with the air sampling temperature probe. (4th picture, upper right) It is just hanging off the PCB and needs to slide down the PCB's air tube before re-assemby. Replace the 10mm bolts around the rotary *****. The 4th picture shows the PCB and switches lined up but not inserted.

 

Hook and snap each of the 2 main harnesses in the rear and slide the CCU back in until it clicks.
The 'top' connector hinges on the right and snaps on the left, while the 'bottom' connector is the opposite

 

That switch 944 653 921 00 is now over 200$ from FVD (!)
And about 120$ for the AC switch.
I guess I'll repaint mine in black....

 

I used crazy glue. So far, 6 months later, all is well.

 

I tired crazy glue, at first it didn't hold. When the button's insides break away, there isn't much left besides an empty shell to glue to. After I did the replacement, on the old switch, I tried crazy glue again- this time I glued the switch up and 'off' whoops Maybe warm Fun-Tak inside the button would do a nice job of holding it in place, or something more commercial/permanent like caulk. I paid $144+tax for the double switch.

 

I just went to order part number: 944-653-921-00 and was told it's 129 dollars for the switch? Does that sound right? Am I ordering the wrong part? Sometimes I just cant understand how it's possible that they can charge that much for something so simple...

 

Yeah I paid a little more, but do see it on Sonnen for that.

You have to make sure it's the exact same double (Defog/Recirculation) button as the CCUs varied slightly.




Anything 'fan' related is very expensive it would seem

 

Hi Laker,

How were you sure about the part number? Is it simply a matter of ordering the switch based on your car's model year?

Were the contacts simply pressed in? No soldering?

Thanks for the write up. I need to do this for both switches.

 

If your CCU has two buttons on the right, with the upper being recirculation and the lower being De-fog / De-frost windshield, it's the right part number. The single part contains both switches. (Re-circ & De-fog) They plug right into the green board (no soldering). You can see the slots on the right and left edges of the green board.