i think this may be the cause of my heat/AC only blowing through the defroster vent. i read somewhere that there is supposed to be a hose going from the heater control box at the firewall to somewhere. i guess its common for it to fall off. well i found that hose i think and it's attatched to where it needs to be, however the other end of the hose at a Y fitting is hooked to nothing. would this cause my air/heat to blow through the defroster only?

box the hose is connected to.


other end of hose going into Y fitting with a hose going nowhere.

 

dont think so, see that black cylinder box in the background on the firewall? thats the vacuum port for the heater. i see the hard line going to it for your controls.

 

hmm. i can turn the temp from cold to hot and that works, but no matter what setting i put the fans on they only blow out the defrost vent and only at one speed. i got the AC working on this car today so i figured i might as well try to get it blowing out the right vents. it's an 83 T/A i bought 2 months ago with a spun rod bearing so the motor was out of the car and in pieces. that a buddy of mine rebuilt and now i'm trying to go through the car fixing little things.

 

On those ealier 3rd gens the vacuum like routing for the HVAC controls goes roughly like this, from memory.....

From the vacuum fitting on the intake manifold behind the carb it goes from there to the "miniature mailbox" vacuum reservoir on the firewall near the powerbrake booster. Should be a fairly big vacuum line- like 7/32" or so.

A second line exits the "mini mailbox" and goes to the HVAC controls up under the dash. This is a factory installed "hardline" with a rubber fitting on the end to seal up against the vacuum nipple on the vacuum reservoir.

Looks like you have the factory line from the vacuum reservoir to the the HVAC controls under the dash. But you're missing the line from the intake to the reservoir to supply they whole system with vacuum from the intake.

Defrost vents are the default position in a 3rd gen if there is no vacuum to the HVAC cntrols on the dash controls (hot/cold is a cable-actuated system and isn't affected by vacuum or lack thereof).

 

ah. makes sense. i think we capped a bunch of crap off during the install of the motor just to get it running. i wonder where that line is at now? could that be the open line i found in the second pic?

 

You still have a factory vacuum line routing diagram plastered somewhere under the hood?

 

not that i know of. the hood is a 305ho hood and the car wasn't a 305ho (it did have a turbo hood origiinally as well but i think the hood and right fender have been replaced.) the core support is just painted black, no stickers whatsoever.

 

SUCCESS!!! as it turns out that was the right hose. the little extra end at the Y connection fit perfectly onto the mailbox fitting and the hose wasn't connected to anythibng on the other end. i took off the air cleaner and sure enough there was a cap on a fitting on the back of the carb that was the proper size for that hose. i hooked up that hose, started the car and immediatly had air blowing out the regular dash vents! thanks for the help.