Capoeirista

I thought that I would make this write up for anyone experiencing A/C issues or concerns after a V6 to V8 swap. My particular swap was a base model 2.8L Automatic 87 Sport Coupe to a 5.0L w/auto with eddy 600 w/ electric choke. The thing that killed me the most was that when I finished my swap I really wanted to do what the sticky said which was RIP out the ECM throw it in a Bonfire and dance around naked! But...the more I thought I realized that I live in Florida and it gets hot as ba**s out here and if I ever wanted to go anywhere with this car my wife wont come close to it without A/C. Sure, if its a nice day and the T-Tops are down that's another story but if its crazy hot and no A/C then you'll never here the end of it!
So I searched around the Forums and really didn't get any definitive answers relative to this swap and could not find a wiring diagram of any value even for cars pre-ECM with A/C Wiring. Everything just kept saying check the LS-1 swap articles and such but nothing that made me feel comfortable with what I was doing on my swap. So....after sitting down and studying the basic wiring diagrams in Chilton's as I do not have a GM shop manual nor easy access to one this is basically what I did....
FIRST.....I decided I needed to keep the ECM for one reason only. If I kept the Ecm a/c circuit intact then it should function as it would anyway as if the car was still being run off of the Ecm and should cycle as needed per the pressure settings in the switches. The computer itself would throw trouble codes all day but who cares when you do this type of swap and have the luxury of living in Florida with no State checks! So studying the Diagrams you can see how the circuit works. These are your main wires in the circuit. I have a flex fan set up so the wiring for the coolant fan relay is not essential for my particular function here.


PINK/BLACK 10GA...Hot in Run 12V Running from fuse block to the Ecm which provides power for this particular circuit
BLACK/PINK 14GA...Connected to the pink/black wire from fuse block by connector which runs this power to the a/c compressor relay
LIGHT BLUE 14GA.....Sends/Recieves signal to the PCM/ECM for cycling of the A/c compressor relay
DARK GREEN/WHITE 14GA......Sends/Receives signal to the PCM/ECM for the A/c compressor rely
BLACK 10GA....Chassis Ground from you compressor clutch harness




CONTINUED...........

Capoeirista

So here is what I did. Completely pull the Passenger side wiring/ECM Harness out of the vehicle for ease of project. Follow the black/pink, light blue and dark green/white wires from the a/c compressor control relay to their respective locations of the connectors for the Ecm(which are black) and the other connector that is white. The light blue and dark green/white will run to the smaller black connector to the Ecm and the black pink will run to the white/clear connector to receive its hot in run 12V so the relay will have power to function. (See Pics ECM Harness 1, 2 and 3) Mark the pin of the connector that the wires run to. I just used some of my wife's yellow nail polish. Once everything is properly marked go ahead and start ripping out the wires from the pins like a mad man! After this is done you will have your connectors completely empty with the entire harness on its own and the a/c compressor relay circuit on its own. Now you can straighten up an clean all the wires for this circuit so you have a nice clean set up. After that is done you can relocate the relay to the passenger side for further cleanliness and begin the process of reassembly. (See pic A/C Setup, compressor relay is right below high side port) Just take the pink/black, light blue and dark green/white and plug them into their respective connectors that you had previously marked and and begin to re route them back into the passenger side to connect to the ECM. ( Again see Pics ECM Harness 1, 2 and 3) Once you are done get your test light out and double check continuity “in run” and make sure you have proper ground. You should be good to go with a/c and clutch should still engage and disengage (cycle) as need through your low and high side switches! You may still have to manulaay adjust the switches to get them to cycle correctly but you are 95% of the way there.
I couldn't get that satisfaction of burnin' my ECM but hey, at least I wont be driving a portable sauna all the time either! The engine bay still looks decent for a daily Driver with no crazy wiring mess anywhere.(See Engine Bay pic) If there is another easy way that any of you guys have done this without the ECM by all means let me know and contribute to this thread for anyone that may need it in the future!

Pocket

iTrader: (24)

I hate to say it but you simply saw LS1 swap and ignored the info in the threads. LS1 swap AC can be broken into 3 categories:

Non-AC
LS1 AC
3rd gen AC

Since swaps happen all the time into older cars and people will always be cheapskates, swap retaining factory functions will remain common. Somewhere along the lines you will have ran across this diagram. I know, because Ive posted it several times

http://www.austinthirdgen.org/mkport...F_and_vin8.jpg

You can see the ONLY ECM wire is along the call side. This lets the ECM know when to bump up the idle so the engine doesnt stall when you turn on the AC. It can be cut out since you are using that fossil of a carb

So feel free to set that piece of aluminum on fire and dance around naked or whatever you crazy florida folk do when you accomplish something

Pocket

iTrader: (24)

To expand on your ECM problems, you have the ECM wired wrong and the MIL hooked up wrong

Your MIL(SES) light is ran through the ECM which goes through the C207 to your dash cluster. Since you didnt connect it at all, the light isnt coming on from improper sensors or a wierd responding ECM. Its coming on because it cant find the ECM at all (no codes, just constant MIL during run)

Next, even if the AC system DID require some for of ECM to be in there, you didnt wire it correctly to work. The ECM requires more than just one IGN source. It needs battery 12v at two pins and 6 grounds. Thats just what is required to turn it on, not the minimal sensors needed to call AC. The engine must be running so it will expect readings from the dist module and TPS. Since it will see neither it will assume engine RPM = 0 and not call the AC. Yours works because the ECM wire you used is simply to bump up the idle and not to control AC at all

The engine wiring can be cut down from this



To this