anyone know basically how they work. trying to figure out if it's possible to make them work in a thirdgen to control the heat only. i no longer have a/c and my hvac control for heat works on more of a lever system then vac but if anyone has any suggestions i'd appreciate it.

 

It runs off vacuum from the engine... Turning the control **** to vent, defrost, etc. allows vacuum through the lines to canisters on the hvac box mounted on top of the trans hump under the dash... The canisters open corresponding doors allowing the air to the dash, defrost, and floor vents... The temp is controlled with a cable that opens a door near the heater core... I would think both systems in 3rd and 4th gen are a similar design using vacuum and a temp cable.

 

thank you for the ideas.. i'll have to look into it. most of the vacuum parts are in the bay on the thirdgen or under the dash so i'll have to see what matches up.

 

If you go HERE to shoebox's site, you'll see what lines go to what and the colors on a 4th gen... You should be able to get a control panel and vacuum hoses off a 4th gen and plug the vacuum lines into the canisters on the 3rd gen HVAC box... At least that seems logical... You'll have to splice into the vacuum line coming from the engine though... The temp cables are a different design... I know the 3rd gen have a slide temp adjuster and the 4th have a rotary type... They both work on the same push/pull principal though... Hopefully the travel of the cable is equal with both gens... You'll have to change the end that goes to the temp door though to fit on a 3rd gen... Not sure about the fan speed though.. 4th gens have 4 speeds... Hopefully they will hook up to a 3rd gen with some splicing in the wiring... You've done a lot to your car so I'm sure you'd have no problem doing all that ... Nice car.