the r32 gtr is also notorious for having a problem with the a/c blend door
i fitted the proper ambient air temp sensor to mine (still available brand new from nissan japan) but still had the same problem as you, you can feel under the dash & there is a pug on the base of the ac unit, if you push on the plug it can open the blend door so it blows cold air, google it, some people have fixed by wedging something in there so the plug makes better contact, the proper fix is to resolder the internals of the unit
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