Corvalliscraig

Hi, I bought a replacement used CCU as my defrost flap wasn't working. (it worked when 12v applied to the CCU plug). This now works but the buttons for recirc and defrost won't latch. My unit is non AC so the switches are full size on each side.

Has this happened to others? If so how did you fix as I've tried switch cleaner, lighter fluid, wd40 to dissolve any hardened grease without success.

931guru

There is a tiny "dog bone" inside the switch which is broken. You need a new switch. (Or a toothpick to keep the button down... LOL)

URO is now making aftermarket copies of the AC switch... time will tell what their half life turns out to be.

Corvalliscraig

I feared you'd say that. I also wondered if some versions latched electrically instead of mechanically. Thank you

DSMblue

If you still have your old unit, you could get the parts out of it and use them with the new replacement unit.

Corvalliscraig

Both look identical. But one ends 01 and the original 03 (very different with much smaller components and the buttons are different . Plug versus soldered)

bonus12

It appears replacing one of these switches may require a higher level of soldering experience, as they are soldered to a board behind the dash. Is there any other to make the latch again?

Corvalliscraig

Well beyond my experience. It's need new switches to replace and probably nla. It'd be easier I'd say to replace the Siemens chips in my old one. I've also seen a thread on here where the poster replaced the latch with a watch pin. None of these are where I want to go. When I think about it the two switches are not really needed as it's only driven in summer (defrost and recirc both redundant) however, I'm selling her so they are needed.

bonus12

Can the buttons of the switch be pulled off? I don't want to try without knowing. I'd like to take a look at that wishbone component and assess things.

931guru

No.

Corvalliscraig

So. Thanks to Tom and all the threads and advice, I'm making progress and learning. Sole oids click when 12v applied and vacuum tee'ed into the axial connections. Output to the Recirc flap and heat control valve. I've two questions
1. When I start her I get vacuum but when I put my finger over the end it's very faint with no power. Is this right? . All the vacuum pipes under bonnet (hood) are good condition, no leaks I can find.

2. I can't see where the vacuum comes from. Must be brake booster?