1987 SWB 4x4 AC Blows on floor

[Toddbo34]

Trying to get my Son's truck fixed up for him for his 16th B-day. Working on the AC now. Problem is that the AC will only blow on the floor unless you move it to defrost. Then it blows a little out the vents. Anyone experience this issue?

[tucsonjwt]

I have not had that problem, but I would suspect the cable to the blend door or the blend door itself has a problem. If you look at the graphic in the LMC catalog for HVAC parts you will get an ideal of how it is connected.

Unfortunately, there are also vacuum canisters that operate the HVAC doors. If you search for HVAC on this website you will find a rebuild of the HVAC system which involved replacing the actuators and the heater control vacuum switch.

I lucked out and just replaced the end of a vacuum line that had rotted away, so I still have the canister and vacuum switch somewhere out in the shed. The factory vacuum lines and fittings are no longer available (as far as I could tell) so you will have to rig something up to replace them if necessary.

I would start with checking all of the vacuum lines and connections. You should take off the dash pad and remove the glove box before you start. You really need access from the top to work on those HVAC parts. The dash comes off without very much effort.

[85gmcguy]

http://67-72chevytrucks.com/vboard/s...d.php?t=460942

I put this together back when I was having defroster/AC/heater problems. It might help. Sounds like a vac problem or maybe the "blend door actuator" Good Luck!

[Toddbo34]

Originally Posted by 85gmcguy

http://67-72chevytrucks.com/vboard/s...d.php?t=460942

I put this together back when I was having defroster/AC/heater problems. It might help. Sounds like a vac problem or maybe the "blend door actuator" Good Luck!

WOW ! Thats a very impressive write up and detailed explanation. Thank you a million and one times. Looks like I may as well just tear it down and redo it all right the first time. Thanks again.