How to Pacify the A/C hi-lo pressure switch for the PCM?
#1
How to Pacify the A/C hi-lo pressure switch for the PCM?
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???
Anyone wanna test their charged LS car A/C and let me know what the reference wire sees when the pressure is normal???
#5
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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.
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wire up like this https://ls1tech.com/forums/conversio...m-drawing.html I modified my VA switch port to accept the LS switch.
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#8
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.
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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.
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.
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How's the build going Bob? Did you figure out everything you need with your VA setup? Well, cept the switch.
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How's the build going Bob? Did you figure out everything you need with your VA setup? Well, cept the switch.
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.
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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.
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.
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.
#14
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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???
Anyone wanna test their charged LS car A/C and let me know what the reference wire sees when the pressure is normal???
T,
#15
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.
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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.
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,
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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.
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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.