MCC sticks on defrost mode. 1998 S70

[skroggur]

The mode selector works as usual immediately after I turn on the ignition. I can select the different modes and hear the dampers and the air comes out of the right places.
However, sometimes when I have been driving for a while, and then want to change the mode, it goes to some kind of unresponsive state where it is in defrost mode regardless of what position is selected and the recirculate button doesn't light up when depressed.
The fan speed control works as usual.

There is a code stored on the unit, 351 (see video), but I can't seem to find any information about that.

IMG-6265.mp4

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Any information/help would be appreciated.

[scot850]

I think this article mainly focuses on the ECC unit but it does have a list of codes and some more information on the heating system:

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://automotivetechinfo.com/wp-conte ... -Early.pdf

I don't have much experience with the MCC units, but hopefully someone else does. I know there is a small circuit board in the MCC unit behind the buttons. If you need a replacement I think I have one if you can't find one locally.

Good Luck!

Neil.