Page 10
Test Points 1-22
Test Points, Fault Codes
Test Points
Test Points
Fault, fault code
Possible causes, elimination, notes
Test point 1
Data lead, air conditioner -PCM
Open circuit/short to ground
Short to B+ Signal disturbance
Fault code 20
Open circuit/short to ground
1. Pull off plug II on the display and operator control unit.
2. Pull off plug C on the heater / A/C control unit.
3. Check lead from plug II pin 15 to plug C 12 for continuity and short to ground.
This is a source reference. Confirm exact model applicability in the original material.