[s-cars] Climate Control diagnostic help

[Kevin Day]

I'm hoping someone else has had (and solved) this problem...

My heater doesn't get that warm. It gets warm enough most of the time,
but sometimes I want it just a couple of degrees warmer. Even on HI, the
air coming out never gets above an estimated 70 degrees F.

I looked at all of the diagnostic channels last night, and there are no
errors reported. Most values that I can make sense of look fine. Coolant
temp is reported to be 92C. This is after a 20 mile highway drive in
~30-35 F ambient temperature.

Selected sensor values:
71F - (ch. 56) - headliner sensor
78F - (ch. 57) - instrument panel sensor
40F - (ch. 58) - air intake sensor
36F - (ch. 59) - outside front ambient sensor
48F - (ch. 60) - air blower ambient sensor

The value for channel 57 seems a bit high. Is this normal?  

The diagram in ETKA seems to imply that the heater valve is on the
return side of the heater core, and the temperature sensor is on the
send side. So it's possible that the core is blocked and too little
coolant is flowing through. Is there an easy way to test this?

Any ideas appreciated.  Thanks.

-Kevin
'94 S4