MeanYellowZ

iTrader: (19)

I have read enough into the way the PCM/ air conditioning works with the LS1, and I want to figure out what it needs to trick the PCM. The PCM supplies 5 volt reference and ground to the pressure switch like most engine related sensors, then it receives feedback from the sensor side of the switch. I am looking for the voltage it takes back to make the PCM "happy." With the Vintage Air in this car supplying its own low pressure switch to reference, I would just like to run the compressor through the PCM so it can correct idle/ fans/ etc. Wiring and mounting in another switch in a new air conditioning system which should not need it just doesn't sound like the best way to go to me.

Anyone wanna test their charged LS car A/C and let me know what the reference wire sees when the pressure is normal???

flyinsquirel

Gettin ready to install a Vintage Gen IV myself and would like to just use 1 sensor also. Anyone?

flame

iTrader: (13)

Its a 5 volt sensor so if pressure range is 20-440psi the median of that would be 210psi 2.5volts which is a normal high side pressure reading. Not sure if it will work to trick it but its worth a try.

garys 68

iTrader: (1)

I've got Vintage Air on my LS conversion. I control the fan through temp (computer) and the VA trinary switch. Not using the computer for any controls. I dont have compressor cutout or increased idle speed capabilities, but I hardly notice any difference.

69 Ghost

I'm looking into using the pressure switch adapted to the VA system. I have not contacted them yet but I expect DB's to provide me with an adapter. I am also using the LS1 variable compressor. Everything should work as planned.

MeanYellowZ

iTrader: (19)

I had been unable to find a direct adapter until today ( I think). I should have it in my hands in a few days, if it works out I will post information.

ssduane

iTrader: (3)

wire up like this https://ls1tech.com/forums/conversio...m-drawing.html I modified my VA switch port to accept the LS switch.

MeanYellowZ

iTrader: (19)

I had found all the drawings/ diagrams. Was mostly interested in tricking the PCM into thinking the pressures are okay and leaving the V/A binary switch to do its job and avoiding having to cut into the system somewhere to install the metric LS A/C pressure sensor. If this adapter fitting works out like it should I will go this route.

ssduane

iTrader: (3)

shoot me a PM if the adapter works for you please. What I did with mine was ran a die over the VA adapter, pulled the needle out and filed the VA adapter flat and down a bit to accept the LS AC switch. It doesn't seem to leak but have only had static pressure in it of about 50-60 psi.

I did the install in December 09 and when I was home on vacation (Mar 10) I checked the system pressure and still had 50ish psi in it, so don't know if it leaks, but still might once I get it up to operating pressure. Won't know until I till I finally move home beginning next year. I am making a run home next month and will check it again and might even get some time to hook up belts/tensioner and operate it and put a full charge in it.

BBPanel

iTrader: (4)

Post it here so we can all take advantage of the info if you don't mind.

ssduane

iTrader: (3)

ya, that too. Just asked for a PM since I will get it via email since I'm not on here much with work and all.

How's the build going Bob? Did you figure out everything you need with your VA setup? Well, cept the switch.

BBPanel

iTrader: (4)

I'm being a little slow - got the unit mounted now trying to figure out where to run the lines to hide most of them - the a/c lines probably under the inner fender. Does/can the LS1 pressure switch replace the binary/trinary switch on the drier - or is that the issue - that is the LS1 is metric and won't thread on directly? Is that the only thing from the LS1 side that needs to be acquired? Obviously the size/shape/location etc of these fittings need to be taken into account since I'm trying to hide most of it in tight quarters. Finding a spot for the drier is not ideal - if under the inner fender on the firewall its not very accessible but I'm not sure where else to put in.

Another unexpected set back - was going to run the oem controls with the rheostat conversion from VA but they hit my wiper motor (Lane relocation kit under the dash) so I had to purchase the custom 3-**** controls and that will now require a little sheetmetal work that I hadn't planned on.

ssduane

iTrader: (3)

yes, the LS switch can go on the drier, if you can figure out how to mount it. I'm not so much trying to hid my hoses, so, runing them wasn't an issue, just want it clean looking. I put my drier right off the condenser, pass side of the radiator. Should be able to run them out the fender well from there.

Gotta love running into snags, these dashes get awfully full once we start shoving stuff up in them, still ahven't had a chance to look at my wiper setup.

TomM

iTrader: (56)

Hey Mean, you know if you tie the AC request signal from the PCM into the clutch, it will do what you want...fans on, and adjust idle......
T,

MeanYellowZ

iTrader: (19)

yeah...if it were only that simple. The PCM has to get feedback from the pressure sensor for high and low system pressure, then decide if it wants the compressor on. It doesn't work just hooking it into the a/c request, it's only happy if it controls the compressor events. If you want it to bump idle/ turn on fans/ drop compressor at WOT it has to be hooked up(or tricked) with the pressure sensor.

TomM

iTrader: (56)

Odd....that's how mine is hooked up and it works. I have Classic Auto Air, and hooked dk/green/wht #17-AC request, to AC clutch +12v and it brings in both fans, and maintains even idle, no drop in RPM. No other wires connected jumpered etc....2000 PCM...

PCM uses RPM to drop fans and A/C above a certain speed, you can set that parameter in tuning software, or defeat it totally.

T,

MeanYellowZ

iTrader: (19)

How could the PCM drop A/C if it's not controlling it? magic?

TomM

iTrader: (56)

My bad, not A\C compressor, just cooling fans.....

T,

BBPanel

iTrader: (4)

Did you get this to work?

Wing Zero

I can be that simple. You can use the pressure switch from the aftermarket A/C. and not use the LS1 RPS (Refrigerant Pressure Sensor). And still get the same thing with out the worry of pressure problems. On vintage Air (I don't know Classic Air set up) tie the A/C request wire to the blue wire on pressue switch (if you have a relay set up like the factory wiring). If not then put a the blue wire to the A/C clutch status (#18 on RED PCM dark green) the computer will see the voltage on that wire and act as it should. The WOT shut off is preprogramed in the computer. And is set with TPS voltage. Unless you change that in the program it will always shut off at WOT. Now you will have to turn off the codes for the RPS. But other that that I have yet to come up on any other problems. Hope this helps.