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tucsonjwt · 10-03-2015, 03:15 PM

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.

10-03-2015, 03:15 PM	#2
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,198	Re: 1987 SWB 4x4 AC Blows on floor 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.