How To Replace A/C Control Unit in Dash?

[OG 8 Lug]

My controls for my A/C don't fully work. Only the Hi and Off settings work on the fan speed. I have additional unit sitting in my toolbox that I want to install to see if I can fix this problem. I did a search on how to do this and came up with things that were slightly different or too vague. I know it's really simple, I just don't want to miss something important and start a fire or some ****.

[slow93]

mind telling us what year truck your trying to work on?

[OG 8 Lug]

My bad, 1996.

[Z-mans Z-71]

How I did this is I turned the key to run(don't start truck) and pull the shifter all the way down. then pull the bezel off the dash and lift it out of the way, you may have to unplug airbag switch and box light switch. Then squeze the retainers on either side of HVAC controls and pull it out, unhook wires and then reverse order on the new unit .

[slow93]

yea , what he said ^^^ its not really hard at all

[1ugly88]

in my experience it's usually the blower resistor that causes that.

[mattillac]

http://www.genmotorinfo.com/images/179864986/420001094.png
http://www.genmotorinfo.com/images/369650793/371923915.png
http://www.gmpartsgiant.com/

http://www.autorepairfacts.com/wp-content/uploads/2008/11/789680971.gif
http://www.autorepairfacts.com/repairs/gm-blower-motor-works-on-one-speed-only/

Maybe the blower motor resistor is defective(open/used thermal fuse), the resistor is for the speeds that are missing(all except high). There is also a high speed relay, and the switch you mentioned swapping out.

My OBS had melted the connector on the back of the selector switch at one time, and on a separate occasion my blower motor was making a screeching noise when first starting up until finally(months later)the thermal fuse on the blower motor resistor gave out from being overworked, I should have replaced the noisy blower motor sooner but instead I wound up replacing the resistor too.

Maybe you could disconnect the resistors electrical connector and then test for power coming from the fan speed switch which should prove the fan speed switch is good and if that is alright then pull the blower motor resistor and check the thermal fuse for continuity.

Below is a link describing how to replace a thermal fuse without having to buy the entire resistor, if that is the trouble and you wanted to try and save a few bucks and kill some time:
http://www.moabjeeper.com/articles/technical/articleImages/515/2281.jpg
http://www.moabjeeper.com/articles/technical/listing.cfm?articleID=515

Below is a post from a fellow FSC member about the resistor/location.

heres a video i made how to troubleshoot what it could be, switch, resistor, or High speed relay.

http://www.youtube.com/watch?v=Acc3JNbUtxo

Below is a link with some nice photos of a dash coming apart.
http://www.dieselplace.com/forum/showthread.php?t=230913

Good luck.

[OG 8 Lug]

Thanks guys. I figured it was that easy, just didn't want to miss any small steps that could cause other stuff to happen. I'm just going to replace the switches first and if that doesn't work, I'll just leave it. I'm about to sell the truck anyway so I'm not too worried.