Jaysz28

iTrader: (19)

Bone stock ls1/T56 in a 82 Camaro. Using the fbody compressor and PCM.

Got around to hooking up the AC this week. The system held a vacuum and took the charge just fine, but the compressor would not kick on.

Time to start chasing wires.

I found a great thread that had a perfect diagram for me to follow.

http://www.thirdgen.org/forums/ltx-l...ml#post4345712

I verified each wire and discovered a dead short on the green wire to the compressor from the relay. Plus the relay was not wired correctly.

So I started over with a new relay. Here is how I have it wired up.

Red connector
14) AC pressure sensor signal to pin C on the pressure sensor
17) AC request signal 12v from the hvac panel
18) AC Clutch supply voltage to relay #87 and to the green wire on the compressor
43) AC Clutch relay control to relay #85
57) reference ground to pin A on the pressure sensor

Blue Connector
45) 5v to pin B on the pressure sensor.

still, I have no ac.

I have 12v at pin 17 with the ac on.

If I ground relay #85, ac compressor will run. The fans come on and the idle comes up. I left the low pressure switch on the ground side and let it run for awhile and saw vent temps at 50* while idling in my garage with 90* ambient temps.

I cannot get the PCM to turn on the ac.(ie ground the relay)

My only two thoughts are this.

1) The PCM reference ground is not hooked up???? I am not certain which reference ground to look at.

2) Possibly the AC is turned off in the tune. I will cough up the $100 tonight and buy some credits for my HP tuners.

Does anyone else have any input? It seems as if the PCM is doing its job when I ground the relay.

A possible work around I have thought of is to piggy back the AC relay #86 and #30 power (with a fuse) off of the AC request signal under the hood. Then just leave the relay grounded (through the 3rd gen low pressure switch). That way the relay is only energized when the ac is requested.

Not my favorite option, as I would rather have the switch on the ground side of things.

Again, any suggestions from those of you that are more experienced with wiring than I am.

Once this is tackled, time for an alignment, window tint and cruise control. If the AC stays this cold, this will be a great, fun daily driver!

1964SS

iTrader: (1)

Have you tried to fool the pcm that the pressures are good to see if it activates? Might be something to test out. I think the blue 55 on this diagram is a mistake it should be blue 45 like you have listed to red 14 with an 80k ohm resistor.

Jaysz28

iTrader: (19)

No, I try the resistor idea

I forgot to mention that the ac shop saw 4v at the pressure sensor, but could not get their scanner to trip the relay. I later discovered that it was not wired correctly......

I will download my tune and see perhaps do some logging now that I am home from work.

I appreciate the suggestion though!

Jaysz28

iTrader: (19)

Well just to update my own thread......

I go out to log what the PCM is seeing. I just turn the key on to see what the PCM is seeing. I slide the lever over to max ac. I see the ac request turn 'yes' on the scanner. I have 1.17 v for the sensor.

then out of nowhere, I hear the distinct 'tink' of the ac clutch engaging.

AC clutch engaged turns yes, ac active turns yes.

I am freaking out..... what just happened.

I turned the key off, turn off the ac. start the car

start logging.

ac sensor = 1.17v
ac fitted = yes
ac requested = yes
ac active = yes
ac clutch engaged = yes!

and its blowing cold ac!!!!!!

unreal

and I am not really certain what I've done besides what I have posted.

so it works....... maybe tomorrow it won't, or it will work fine until I take it back to the ac shop for them to check the pressures and make certain everything is good.

I can book my alignment now though.... w00t

thanks for the support LS1tech. I found most of my answers searching, so I count that as support!

-jason

Jaysz28

iTrader: (19)

so now it isn't working.

I verified the 4 grounds at the PCM on both the red and blue connectors pin 1 and 40.

I have not checked pin 57 continuity to ground yet.

Pin 43 is supplying 12v+ to the relay, not a ground signal. If it is supposed to be a 12v+ signal, I can make that work by grounding the opposite side of the relay. The diagram does not read that way to me though.

so close yet so far.

Jaysz28

iTrader: (19)

Something I noticed while staring at the schematics of the AC circuit is that I do not have a diode on the compressor plug. It seems that the only potential problem I would have from that is blown fuses from a possible voltage spike when the compressor kicks off.

I can order a new pigtail, or go find one at the bone yard. The pigtail I am using came off of a v6 car, which obviously did not have the diode.

makes me wonder why one needs it and the other does not.

Dan Garland

I'm having the same issue did you find a fix ???
I don't think I'm getting ground at pcm red 57 Did you bypass or fix your problem if I ground the relay at 85 it kicks the compressor on In the wiring diagram it shows pcm red 57 goes to low refferance and it tees to iac Show to be ground purple wire When I put a meter on this wire it's not showing ground
Did you find the fix for your problem and maybe you can share your findings
Thanks

Pocket

iTrader: (22)

There are two primary methods to approach this

1) Full computer control and pressure protection

2) Independent control with mechanical pressure protection

For the first method, emulate the 99-02 Fbody diagram exactly. Use the three pin pressure sensor (note, not a switch) in the high pressure line

For the second, use the AC request to trigger a relay giving power to the AC compressor clutch. Use 80's high and low pressure switches to interrupt power to the compressor clutch when pressure is outside of specs. A return wire is advised to the PCM after both pressure switches

heykw

Gbody boy

Hi I am new here I am in need of help with setting up my ls swap a/c in my g body car. Can you guy help me??

Old Geezer

iTrader: (3)

G body boy: Suggest you start your own thread....

towstrap4x4

Subscribing

G Atsma

To what? A thread that went dead awhile back, or one that was asked to start elsewhere?