Wiring LT1 a/c
 

Basically what to know how to wire a/c.

I got the a/c request wire connected. I'm looking at the HVAC schematics for the f-body LT1. There are 2 sensors used. I have one of the sensors and its still on the LT1 accumulator but i'm not going to use the LT1 accumulator. Do you need those 2 sensors?

http://shbox.com/1/hvac_compressor_control.jpg

I am using the factory wiring for my car. I am using none of the sensors for the LT1 computer. The factory HVAC runs through the cycling switch. The blue wire coming out goes to the compressor(on some cars it is green). This same wire also goes to the A/C clutch status on the PCM. The A/C request comes from the control head side of the cycling switch. My A/C works I only have to replace the condenser because it is clogged giving me ridiculous line pressure. I am not running the request wire, because it is supposed to trigger a relay on LT1 cars. I do not have a seperate relay for A/C so it isn't neccessary.

are you using the thirdgen ecm? Or do you know if you need the thirdgen ecm. I took my old ecm out but i could put it back in.

I am using the LT1 PCM. I haven't had a factory ecm in years, I would have no use for it.

ok, i thought the thirdgen ecm was needed for a/c but looking at your schematic, the thirdgen ecm is used as an input, so it isn't needed. Cool.

As long as the LT1 PCM gets a signal that the A/C is on, there should be no problems. Some people don't interface the A/C with the PCM and have no problems. I want mine hooked up just in case.

I will have mine wired up using the 4th gen fuse box so I can have the fans come on when the a/c is turned on. People who have their fans hooked up using the PCM to control them wire it up through the PCM for this reason. I finally got the 4th gen condensor in place, have to pull the passenger side header to get the hoses in and the upper line made using the 4th gen metal lines with the highpressure switch in it.

Bingo a buddy of mine that does HVAC told me when I had the lines made to check and make sure they were good ones since I'll have over 300lb of pressure on the high side, so you may be ok with yours.

I'm using that overpriced a/c relocation bracket for now, until i pull the engine someday and using thirdgen 3.1L V6 lines. Yep, I want the fans to kick on when the A/C is on.

Due to a bad condenser, my lines have withstood 500 PSI. I guess I made them pretty well. My fans are on by 180 so I don't think I will have a problem with my fans. I used my A/C the oter day and the guage barely moved.

Will the A/C compressor turn on if there is nothing in the a/c system(no freon or oil)? Will the low pressure switch disable it from turning on because nothing is there? I got no voltage at the compressor clutch for some reason.

The system must have pressure to engage. You can jump the cycling switch to complete the circuit if it is wired right.

I have a/c requests(thirdgen and LT1) wired together. I have a/c clutch wires wired together. Fan still does not turn on and no codes are thrown. Now I could probably figure out a way to wire my fans to turn on whenever I throw the switch for the a/c but shouldn't the LT1 PCM be kicking on those fans the way I have it wired now?

My a/c is working. Using bowers bracket with f-body compressor mounted high on the driver's side, 89 V6 lines, (2) a/c seal washers on one of the hoses connected to the compressor, (1) seal washer on the other hose connected to the compressor, the bolt on the back of the compressor was tightened very very tight. So far no leaks.

The A/C request and clutch status are for the idle correction under load. The LT1 has a 3 wire pressure sensor on the hardline that kicks the fan on. I don't have this sensor wired up. I have my fans programmed to come on early and so far they have kept the car cool with the A/C on. Do you have any pics of your setup? I was the first one to post about the Bowers bracket and I have yet to see a pic of one installed.

Re: Wiring LT1 a/c
 

Old thread, but.....


I am leaning towards this swap, where I was thinking LS1, until I came across a too good to pass up LT1.

Anyway.

For the A/C, if the 3 wire high side switch works the fans on the 4th gen, then I would wire the fan relay input thru the high switch, or compressor clutch for fan operation. The fans should be on whenever the A/C is on, or when pressure goes over 200lbs at least. If you don't have the 3 wire switch in your line and your having lines made, it can be added in while doing that easily. :)


Just thinking out loud while going thru the swap in my head. Maybe this may help too?


...Jim
W.E.D.

Re: Wiring LT1 a/c
 

I am using the 4th gen pressure switch with my factory lines. I am going to wire it exactly as a 4th gen. I need to get the temperature probe for the evaporator. I still have to add a relay for my compressor. I have it running through the 3rd gen pressure switch right now and it is independant of the PCM. It bogs down when the compressure engages. I have the A/C request and A/C clutch status connected, but I think it needs the relay.

Re: Wiring LT1 a/c
 

I had a question I am work on a 86 Iroc swap a lt1 from 94 vette what can I use for the fan I am using the lt1 wire harness which the fan conector has 3 wires and the 86 Camaro wire uses two wires can still use the Camaro fan are will look for a Impala are Road master fan?? thanks hope you help

Re: Wiring LT1 a/c
 

hey FIREBAT what kind of fan are you using for the radiator cooling Iam using the stock 86 IROC Z radiator and fan it has a two wire conector and Iam using the Lt1 wire harness from a a 94 vette and it has 3 wires going to fan connector thanks for your help