well - I have read that if I unkook the connector to the monovalve it should be in the open position - allowing coolant to flow through the heater core. I will try that first.
I will also check the ohm range of the signal to the monovalve to see if it's within spec.
If those two check out then there's a good chance it is not my ccu since the ccu would be emitting the correct signals.
The other more dreaded possibility is that it's the vacuum pot that redirects air into the heater core to begin with. I will check the ohm range of the signal emitted by the ccu to that pot to see if it's working properly.
The manual is very good in descriptions of the test procedures.
and of course it could be the CCU itself in terms of the temp thumbwheel rheostat just not working and not putting out the correct signals.
I am hoping it's just the ccu and not the vaccum pots because from all my reading here - they're a real pain to replace.