Need help with AC swap
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From: Starkville
Car: 88 Trans Am
Engine: 350
Transmission: T5
Axle/Gears: Posi
Need help with AC swap
my car was originally gutted as far as the HVAC is concerned. It had nothing in the engine compartment no heater core, no vents, etc.
Im finishing up the swap and i dont know where the two vacuum lines that pass through to the engine side of the firewall go. They are both black. One has a 90 degree bend and the other is straight.
Right now it only blows air out the defroster and under/behind the radio
Im finishing up the swap and i dont know where the two vacuum lines that pass through to the engine side of the firewall go. They are both black. One has a 90 degree bend and the other is straight.
Right now it only blows air out the defroster and under/behind the radio
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Joined: Oct 2006
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From: erlangen, Germany
Car: 1991 Z28 1LE
Engine: LS1
Transmission: T56
Axle/Gears: 3.42
Re: Need help with AC swap
I believe one would go to manifold vacuum, probably the 90° bend. The other one should go to the heater control valve.
Joined: Apr 2005
Posts: 7,736
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: Need help with AC swap
Typically the vac supply from a intake port to the HVAC system goes through a check valve ;
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
Senior Member
iTrader: (14)
Joined: Oct 2006
Posts: 823
Likes: 1
From: erlangen, Germany
Car: 1991 Z28 1LE
Engine: LS1
Transmission: T56
Axle/Gears: 3.42
Re: Need help with AC swap
Typically the vac supply from a intake port to the HVAC system goes through a check valve ;
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
I'm gonna have to dig through my various 3rd gen stuff and see if I can find that check valve. During my engine swap I got rid of my AC system, and this was during an 18 month period so some things didn't make it back like they were supposed to. Thanks for the pic!
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Joined: Apr 2010
Posts: 1,015
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From: Modesto, California
Car: 88 Firebird Formula
Engine: LO5 5.7 TBI/Ebl Flash
Transmission: 700R4
Axle/Gears: 2.73 stock rear end
Re: Need help with AC swap
Typically the vac supply from a intake port to the HVAC system goes through a check valve ;
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
where the rear port goes to the line inside
and the side port goes to the vac ball up front ( with a T off to the CC if fitted )
This arrangement prevents the vent positions changing every time you accelerate and the engine vac drops
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Hello, Michael
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Aug 20, 2015 03:19 PM
