5.3 Vortec AC - How to correctly setup a Chevy compressor to stock 60? (1 Viewer)

[EasternYeti]

Its been three years without AC and i'm trying to cross the last hurdle....I've been cruising some threads and there doesn't seem to be a de-facto guide on AC when it comes to this swap. I know there is potentially a piece that needs to be removed from the amplifier...and i did as a much.

however, This issue with my truck seems to be old Toyota system, it only has a low pressure switch, missing the high pressure switch entirely. As far as i know this is how it was stock??

Can anyone offer some step by step instructions on how they wired up there AC? I don't even care about the idle up at this point, so much as its 98 degrees and i can't exist without it. I have the lines in (Minus one switch, and the compressor is installed but not wired up)

How hard is it to wire up a new pressure switch? and has anyone else needed to do that? Wiring Schematics are more than welcome.

 

[cruisermatt]

@orion did a nice job on his. He posted it in his build thread, maybe he can copy and paste it here.

 

[orion]

^^^ I didn't document anything on the wiring, as it was mostly covered here:
The A/C Amp Thread
(see post #4, remove the resistor so it doesn't reference the RPM)

As far as I am aware, the amplifier is the "brains", and there's nothing else needed...

My understanding is that the amplifier should cycle the compressor if it starts to freeze up the evaporator, and cut the system off if there's no pressure sensed by the low pressure switch (that's on the evaporator / under the dash). Someone please correct that if I'm wrong.

So if the system has pressure, and the RPMs are ignored...you get +12v out on the factory A/C wire.

I used a new relay, triggered by the amplifier output (factory compressor wire), to run my compressor.

To add a high pressure cut-off, I wired the relay (the ground / pin 86) through the high pressure cut-off switch that was on my GM compressor (it's normally closed, but opens up at +400psi or something along those lines).

And that's it.

- Brian

 

[orion]

Here's a quick wiring diagram (note that I am going off memory, but I'm 95% sure this is how I did mine):

- Brian

 

[YotaJosh]

All I did was run the clutch energize wire from the FJ60 harness to the GM compressor (no need in going through the LS harness), and did the amplifier mod. My AC has worked great all summer.

I believe all the pressure switches are handled within the AC unit under the dash. I do know that when I'm low on R134A, it won't cycle, and when I run the fan on low, it freezes up and cycles the compressor as expected.

Edit: when my FJ60 was 350 TBI powered, it was wired the same way.

 

[AggiePE]

I used a similar wiring as orion above, but I used a generic high/low pressure switch on the dryer port. see photos. I got a manual A/C thermostat controller from a local A/C shop (the kind they use on old drink coolers i believe) It has a knob and a thermo-couple that i installed directly into the evaporator inside the cab. I drilled a 1/4" hole in the plastic of the evaporator case and just inserted the probe into the evaporator coils. This will open the circuit if the evaporator gets too cold. I believe its called a "Capillary thermostat"

Link to something similar:
ROTARY THERMOSTAT 48' CAPILLARY Global Air, Inc.

I removed the A/C amplifier (after purchasing 2 and still not being able to get it to work right) and jumped the hot wire directly to the original A/C compressor power output wire. I have not had a lick of trouble out of it since the install and I can hear the compressor cycle on and off at times due to pressure or temperature. It did take about a week of playing with the manual thermostat to get it just right.

I did convert mine to 134a using the factor LS compressor and a set of custom hoses.

Hope this helps.
KK

View attachment 1777820

 

[orion]

^^^ Very cool. More complicated, but another way to skin this cat.

...

Shameless plug: I still have all my SBC stuff for sale...to add A/C to a V8-swapped FJ60 - I'll make somebody one hell of a deal on all of it!
For Sale - FS: FJ60 - Custom A/C lines for V8 swap + serpentine setup



- Brian

 

[Shes Mad]

All I did was run the clutch energize wire from the FJ60 harness to the GM compressor (no need in going through the LS harness), and did the amplifier mod. My AC has worked great all summer.

I believe all the pressure switches are handled within the AC unit under the dash. I do know that when I'm low on R134A, it won't cycle, and when I run the fan on low, it freezes up and cycles the compressor as expected.

Edit: when my FJ60 was 350 TBI powered, it was wired the same way.

I have an LM7 5.3 in my 87. I did the same thing, but put the 62 amp in my 60 instead of modding the 60 amp. Used the big plug, left the small one dangling. Works fine

 

[FJ60Cam]

All I did was run the clutch energize wire from the FJ60 harness to the GM compressor (no need in going through the LS harness), and did the amplifier mod. My AC has worked great all summer.

I believe all the pressure switches are handled within the AC unit under the dash. I do know that when I'm low on R134A, it won't cycle, and when I run the fan on low, it freezes up and cycles the compressor as expected.

Edit: when my FJ60 was 350 TBI powered, it was wired the same way.

Same here. Modified the lines, reconnected the old clutch wire to the new clutch, peeled out. Works as before

 

[BHillteq]

All I did was run the clutch energize wire from the FJ60 harness to the GM compressor (no need in going through the LS harness), and did the amplifier mod. My AC has worked great all summer.

I believe all the pressure switches are handled within the AC unit under the dash. I do know that when I'm low on R134A, it won't cycle, and when I run the fan on low, it freezes up and cycles the compressor as expected.

Edit: when my FJ60 was 350 TBI powered, it was wired the same way.

Thread revival! When yours was still TBI powered, how did you wire it to tell the TBI to idle up when the a/c was on?

 

[YotaJosh]

Thread revival! When yours was still TBI powered, how did you wire it to tell the TBI to idle up when the a/c was on?

I didn't. Made no difference to me.

Edit: There is a wire to send the signal to the TBI ECM and it will idle it up for you. I don't remember which wire exactly. Any TBI wiring diagram should detail this wire.

 

[BHillteq]

I didn't. Made no difference to me.

Edit: There is a wire to send the signal to the TBI ECM and it will idle it up for you. I don't remember which wire exactly. Any TBI wiring diagram should detail this wire.

Thanks for the response! Looks like the signal wire is B8 pin on the ECM. When it gets 12v, it kicks the idle up! Next question is, what do I have send the signal? The factory compressor trigger wire?

 

[YotaJosh]

Thanks for the response! Looks like the signal wire is B8 pin on the ECM. When it gets 12v, it kicks the idle up! Next question is, what do I have send the signal? The factory compressor trigger wire?

That's what I'd use.

 

[dbbowen]

Sorry to resurrect the thread again, but what did you guys do for AC idle up? The idle up signal on the GM stuff doesnt take 12v. Did you guys find a work around for this? Gen3 lm7

 

[Shes Mad]

Sorry to resurrect the thread again, but what did you guys do for AC idle up? The idle up signal on the GM stuff doesnt take 12v. Did you guys find a work around for this? Gen3 lm7

I didnt use idle up on my LM7. It really didn’t need it

 

[dbbowen]

I didnt use idle up on my LM7. It really didn’t need it

Does it not bog the motor down at idle? or run the air hot?

 

[tmxmotorsports]

Does it not bog the motor down at idle? or run the air hot?

Ecm see's a load and idles up automatically

 

[dbbowen]

Ecm see's a load and idles up automatically

I thought this was for Gen4 ECMs. I was reading that the Gen 3 stuff needed a different type of signal

 

[tmxmotorsports]

What year

 

[Shes Mad]

Does it not bog the motor down at idle? or run the air hot?

No. Worked fine. Mine was a 2003 LM7 drive by cable