LSX-affair

iTrader: (1)

After searching and reading pages of threads I still don't have the answers to my questions. I am converting the wife's 68 c10 with a LS2 from a TBSS and would like to use the factory 68 air conditioning. My take out engine came with two trinary switches and I am not to sure of which one I should use? Also, the ac on the truck has been converted to 134a at some point and the POA valve is from Old Air Products. Is anyone making an adapter of some kind that will allow me to remove the old binary sw and adapt the trinary sw to the POA valve? Or what other options are there? Will this even work?

Any help or suggestions will be much appreciated!

Pictures of my two trinary sw and one of the binary sw on the POA valve.

89 formula350

iTrader: (8)

If you remove the switch and it has the standard r12 fitting under it you can use a pressure sensor from a 1990 grandam VIN code "a" or "d" that's been proven to work on many r12 systems. there are many FWD gm cars with r12 that will have the same sensor but the 1990 grand am is known to have this with those engines. hope this helps..


on a second look that's your low side.. you want the pressure sensor on the high side line.. that's your low pressure cut off switch. you should be able to leave it alone or cap it off

LSX-affair

iTrader: (1)

Ok, so I only need the switch on the high side? Would something like this work

http://www.nostalgicairparts.com/air...h-port-376.php

Or does someone make a fitting to take the factory switch that I have?

BTW, what is the difference between the two trinary switches I have pictured above?

Thanks!

89 formula350

iTrader: (8)

Im sure there is a fitting for your r134a switch that you have already. the link you posted I really dont know if that will work. the tube looks like it will fit the r12 style switch I mention before. are you sure you dont have a high side switch? some of those old cycling systems had one on the high side. if thats the case you can remove it and see what fitting is under it.

the sensor with the male fitting you have looks like a oil pressure switch.



Im not going to bullshit you im no expert on these conversions. but with my background I know enough to be dangerous

also look up the wiring for the ls2 and the a/c if I recall correctly the ls2 pcms at least the GTO uses the BCM to run the A/C if thats the case you have more in store for your a/c wiring. the ls1 systems are PCM controlled and are very simple to wire up and have working

arthropraxis

BCM will control one of the fans, too. I just used a F-body PCM and wired the harness to match.

LSX-affair

iTrader: (1)

I did a little reading to find out just how these older ac systems worked. The poa valve I have pictured basically controls the amount of freon to the suction side of the compressor. Another thing to note about this system is that the ac compressor runs constantly as long as the binary pressure sw is closed (enough pressure in the system).

One thing I didn't mention is that I am using a stand alone harness from Speartech. The harness has a green wire 12v call for ac, the trinary sw for pressure confirmation/fan operation, two wires for the fan control primary and ac.

So from the way I understand it all I need to do is find something that will get my trinary sw in the high side of the ac for the ecm to control the compressor. The poa valve will control the amount of pressure back to the compressor. Am I wrong in my thinking?

Here's a description of the poa valve:

Like the suction valve, the POA valve is a suction throttling device that is located at the outlet of the A/C evaporator and is used to control the amount of compressor suction on the evaporator.

The POA valve was used on some General Motors and Ford air conditioning systems through the 1970�s. On these A/C systems, the compressor would run constantly whenever the A/C system was on. Under certain operating conditions, less compressor suction was required on the evaporator. The POA valve would then close off the flow of refrigerant, effectively reducing the amount of compressor suction.


BTW; You were right! That is the oil pressure sending unit... Its been a while since I've been working on this project, I really need to get it DONE!

89 formula350

iTrader: (8)

I'm really not sure how the LS a/c compressor will work with the valve inline. the ls style compressor I think controls this internally through a wave plate that changes its displacement (I may be wrong as its been years).

you might be best off simplifying this setup. remove the valve and allow the compressor to work as its designed with the switch on the high side like you said.

LSX-affair

iTrader: (1)

Wow lots of views! I would have thought more people have tried doing this?

1989 Formula350,
Does this look like a fitting I could braze into a line on the high side for my trinary sw? -> http://www.tubesnhoses.com/proddetail.asp?prod=4166

I did some looking into what you are saying about the ls compressor and the wave plates, I couldn't find much info on how they work. I am going to start looking for a mobile ac guy to come out and look at what I am doing.