Door Locks and Heater & A/C Vents

[Shaggy419]

I have looked around the forum, but doesn't seem like everyone is having the same issue as me, so figured I would start a new thread and get some opinions on where to start. Just recently acquired the Yukon 4 door (1997) and learning some quirks that I know will bug me the longer I let them go. Here are my issues, let me know your thoughts, please??

1. Heater & A/C Vents - When you turn on defroster or any other setting it blows out of all the vents (Defrost, Front Vents, and Floor). What is the part called that controls that?? Or is this a common issue, and easy fix??

2. Door Locks - This one is tricky, and has me stumped frankly... I will start with the switches, and move on to the FOB's. When you hit the lock button, the only door that attempts to lock is the drivers door (If you hit it a few times, it will lock all the way) and you can hear relay click under dash after letting off of button, but nothing from passenger or rear doors. If you hit the unlock, the passenger door and rear doors will unlock if locked, but drivers door doesn't attempt at all (Just like the 3 doors when pressing lock), but can still hear relay under dash after letting go of button. All doors can be manually locked, and they do have a little resistance but not bad, the drivers door seems to have the most resistance. It is not difficult to lock them manually, but can definitely feel a little resistance, especially drivers door... Thoughts??

3. FOB's - Do not control any of the locks at all (Batteries could be dead as far as I know...). Tried the jumper trick, and the relay clicked like it was trying to lock/unlock to let me know it was in programming mode, but didn't do anything at the doors. I understand I have a locking/unlocking issue and need to resolve that first before worrying about FOB's, but my question is, if it tried going into programming mode, does that mean the receiver is good and worst case need new batteries or new FOB's even??

Sorry for the Noob questions, but figured maybe someone here has had same issues and could point me in the right direction and save me a ton of diagnosing... Thanks for your help in advance!!

*Good news is it quit raining so I can get some before pics of the truck!!!

 

[DownFall]

As for the a/c issue. sounds like the door that controls air flow direction is stuck at a midway point, this can be caused by three possible issues. the door may just be stuck, the hvac (dash controls) may be defective as mine were, or the motor that conyrols the air direction door may be bad. as for the door locks sounds like bad door master (driver front) swith and dead bat in fob. but i would need a frw hours my test probe and muti-meter to know for sure.

 

[SunlitComet]

1. check for broken linkages for the output mode control. you will see them just above the gas pedal to the right on the hvac assembly.

2. If one door has more resistance in the lock mechanism then others then there is something wrong with the locking latch mechanism at the end of the door being stick or the power actuator with the same issue. however the sequence of the operation is odd. sure you don't have and aftermarket device taking control of that and it may be set up incorrectly. Door mounted buttons do all at once period. keyless entry could do one push for driver unlock and second for all I think it was.(maybe someone screwed with that and reversed the trigger wires.) lock button should do all at the same time I think. read the owners manual to be sure.

3. the receiver is part of the keyless module. no way to test just the receiver itself. will just need to try a known good fob.