GMC Repair: 2004 2500 Sierra, passanger side, actuator

Question
2 Part issue
Issue: Front A/C was pulsing - meaning blowing hard then soft.  
Action: I pulled the HVAC/ECAS fuse (referenced in a previous post - Air stuck on defrost of 2004 Sierra 2500 HD) - thinking they may be related and now I find myself is issue #2
Issue: Air stuck on defrost.  The air cycles through the different settings (vents, floor, defrost) but then stays on defrost.
I believe the pulsing still occurs - so I basically have gotten myself into deeper trouble.  Any insight/guidance would be greatly appreciated


Answer
Hi
Check the harness that runs down between the glove box door frame and the black HVAC case. You can ope the door ALL the way, past the detents, to see the harness.
Check it for any signs of damage, rubbed through tape, etc....
On the passanger side, with door open, take the IP dash end cap off. There will be an electrical junction block.
Check all the terminals for fit.
If it is OK, pull the fuse again for 1 minute.
See if it defaults, if so the mode door actuator is PROBABALLY your fault. There is also a reprogram for AUTOMATIC air if applicable.
I Hope this helps.
Good Luck
Follow post back, if needed.
Pawl