Primary Junction Bloack is the fuse panel in the passenger compartment below the dash.
The AC Heater Function Switch is the one on the AC panel you select AC Max, ACm Vent, etc etc. It comes out as part of the panel it is attached to using the same tools as are required to pull the radio. You can check for voltage at the clutch connector with the AC on MAX and the Low Pressure Switch bypassed. No voltage and you know your problem is elsewhere.
IRCM is the Intergrated Relay Control Module mounted forward of the Air Filter box.