[s-cars] Climate Control interchangability with B5?

[Tom Mullane]

Folks,

I bought a 1996 A4 for a winter beater.  I have this dream where I
actually convince my wife to take the car to winter driving school...

I'm trying to get the car sorted out and one of the issues is a blank
display on the Climate Control.  The lights work fine, but the display
is blank.  Stabilant 22 has not helped.  I have a C4 CC head as a
spare for my car that I have installed in the A4.  It looks physically
the same and the part number is close (different letter suffix) and it
plugs right in.  However, the air blowing from the vents is not hot -
it's warm, but not hot.  The CC unit is trying to do it's job; it will
run the fan at relatively high speed trying to warm the car with
luke-warm air.  My guess is that the CC is different because the two
heater boxes are different.  It might be cranking the blend door to
"full hot" on the C4, but that might be halfway on the B5.  I also
noticed the the part number sticker says the chassis type in the upper
left corner.
Anyone have any experience with this?

TIA

Tom