Going back to A/C
01-05-2019, 07:22 PM
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Car: 91Z28
Engine: 5.7 ls1
Transmission: 4l60e
Axle/Gears: 3.42
Going back to A/C
Hey guys sorry if I’m starting multiple threads I haven’t post on here for a good while. So on my car I have gone through a lot of setups and I finally have made my final decision since I would like to enjoy driving the car instead of having it parked all the time. So I’m going to be swapping in a ls3/t56 setup into it. My main reason for this post is that I’m going to be running ac this time since I want to be able to drive the car comfortably even when it’s warm outside and living in Cali that means 90% of the time lol. But since I had thrown away all of the ac and heater stuff away when I first swapped in my previous ls swap engine now I need to get it all back. Well at least the stuff I do need. I am running pockets personal harness so he had it setup for 4th gen compressor. So I have been looking into other peoples threads and easiest way seems like if I get all the stock thirdgen ac stuff I should be able to just notch my k member and get the hawks ac line kit and be good am I correct? Sorry if post is long hope I explained myself good on what I’m looking for.
01-14-2019, 09:45 PM
#2
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Re: Going back to A/C
Do you mean to say that you need the 3rd gen HVAC box, in addition to the other parts?
01-14-2019, 09:48 PM
#3
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Car: 91Z28
Engine: 5.7 ls1
Transmission: 4l60e
Axle/Gears: 3.42
Re: Going back to A/C
I have already bought a thirdgen hvac box along with all new ac components. Just pretty much was curious on what people would modify on there ac setup in order to make their ac work. From what I understand all that is needed is the 4th gen high pressure switch.
01-15-2019, 10:07 AM
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Going back to A/C
Hawks AC line will not work with stock 4th gen manifolds.
I just finished this swap (well with a ls1/t56)
Thirdgen compressor/evaporator
Thirdgen high pressure line
Thirdgen dryer
Thirdgen expansion tube
4th gen compressor (or a high mount compressor and bracket to avoid k-member issues -- extending the wiring would be easier)
4th gen high pressure sensor
Check with pocket but you may need to add a relay if it isn't already there in the wiring harness
I had the 2000 firebird lines modified as I'm running stock 2000 exhaust and hawks lines would not clear it. It was actually cheaper at the local hydraulic line shop.
One thing to note the 4th gen compressor is variable displacement so it doesn't cycle on/off when the AC is on that confused me and spent a lot of time trying to figure out why it wasn't cycling. You can modify the compressor to be constant displacement and then use the thirdgen low pressure switch and 4th gen high pressure switch to set it up to cycle. Or if you do a high mount then you can buy a constant displacement compressor etc. I hear the constant displacement works better with the existing thirdgen parts.
The other thing to note the condenser buy one for a 92 not the 89 it will work better with the 4th gen compressor. I've forgotten the terms but the 92 style is the same basic design as the 4th gen in terms of the two ways condensers are designed.
24-30 oz of R134 is where it seems happy on the gauges, 24 is the volume called for for the 2000 firebird. Use the PAG amount and weight the compressor specifies.
I just finished this swap (well with a ls1/t56)
Thirdgen compressor/evaporator
Thirdgen high pressure line
Thirdgen dryer
Thirdgen expansion tube
4th gen compressor (or a high mount compressor and bracket to avoid k-member issues -- extending the wiring would be easier)
4th gen high pressure sensor
Check with pocket but you may need to add a relay if it isn't already there in the wiring harness
I had the 2000 firebird lines modified as I'm running stock 2000 exhaust and hawks lines would not clear it. It was actually cheaper at the local hydraulic line shop.
One thing to note the 4th gen compressor is variable displacement so it doesn't cycle on/off when the AC is on that confused me and spent a lot of time trying to figure out why it wasn't cycling. You can modify the compressor to be constant displacement and then use the thirdgen low pressure switch and 4th gen high pressure switch to set it up to cycle. Or if you do a high mount then you can buy a constant displacement compressor etc. I hear the constant displacement works better with the existing thirdgen parts.
The other thing to note the condenser buy one for a 92 not the 89 it will work better with the 4th gen compressor. I've forgotten the terms but the 92 style is the same basic design as the 4th gen in terms of the two ways condensers are designed.
24-30 oz of R134 is where it seems happy on the gauges, 24 is the volume called for for the 2000 firebird. Use the PAG amount and weight the compressor specifies.
01-15-2019, 10:18 AM
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Going back to A/C
Do you know if the wiring is set up to use the PCM for signalling or direct? I wired mine so the control goes to the PCM and the rest of the wiring is 4th gen style.
I just realized you are who I just sold my unused Hawks lines to -- need more coffee
I just realized you are who I just sold my unused Hawks lines to -- need more coffee
01-15-2019, 12:53 PM
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Car: 91Z28
Engine: 5.7 ls1
Transmission: 4l60e
Axle/Gears: 3.42
Re: Going back to A/C
Thank you Aviator. Yeah I am the one who bought your lines lol your thread popped up when I was looking up what people used to work. Well seems like I pretty much got everything I’m going to be needing for the swap just need to see how the 4th gen high pressure switch has to be wired up since I don’t think I have that one.
01-15-2019, 01:05 PM
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Going back to A/C
I've wired my ac using the diagram in post 35 here.
https://www.thirdgen.org/forums/ltx-...ml#post4248157
The pressure switch is simply a safety check, if the pressure gets too high or low it turns off the compressor. There are a few different ways you can wire it. Well this is true if its a variable displacement compressor, if not the pressure switch cycles the clutch on and off as the pressure varies to maintain the required pressure.
https://www.thirdgen.org/forums/ltx-...ml#post4248157
The pressure switch is simply a safety check, if the pressure gets too high or low it turns off the compressor. There are a few different ways you can wire it. Well this is true if its a variable displacement compressor, if not the pressure switch cycles the clutch on and off as the pressure varies to maintain the required pressure.
Last edited by Aviator857; 01-15-2019 at 01:20 PM.
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01-16-2019, 09:41 AM
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Going back to A/C
One other part, the Bracket to mount the AC compressor which includes the idler pulleys if using a stock 4th gen style set up. and of course the belt.
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