April 10, 2021, 05:55:32 PM

Author Topic: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering  (Read 15355 times)

Offline halfspec

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Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #15 on: October 15, 2018, 09:34:02 AM »
Travis

Sorry for baling after Friday. Long busy weekend and my two year old's birthday kept my schedule slammed.

Merging some data from your PM's - I think the way you've sourced your ground for your meter is fine.  Thanks for all the pictures, they helped get me on the same page. Your testing procedure is solid.

After reviewing your findings, I'm convinced that you've got a good ground signal coming from the blower selector switch and resistor on the white wire that goes to position 1G of the black HVAC connector G-01.
I'm 90% sure you've also determined that the problem is on the output of the AC switch / the Violet/Pink wire leaving position 1I of the HVAC black connector G-01. The only muddiness in the water is you said "No resistance with any combination of car on or off or AC on or AC off with blower position on #1." No resistance to ground with your setup configuration on position 1I would mean your shorted to ground, which means your getting a ground on violet / pint, which is correct, but I have a feeling that's just a typo. Did you mean to say large / infinite resistance?
The reason I had you unplug G-08 was to try and determine if something in your micro relay / AC interceptor was wired and maybe shorting the whole ac switch to ground or something because of your 'no resistance' comment.

If you're getting a large resistance to ground out of the Violet/Pink wire leaving position 1I of the HVAC black connector G-01, I'm pretty sure you've diagnosed a bad AC switch / HVAC board. Which one, I couldn't say since the HVAC unit to regarded as a black box in the FD's wiring diagram. It literally only shows a simplified diagram of the AC switch and that's it, so that makes drilling down any further impossible, at least from my end. You could do a wire check to make sure your AC switch's wiring between the HVAC PCB and the actual switch (I think it's like a 4 - 6 wire jumper connector made of red or white wires) is fully plugged in without and crimped / fractured wiring (you could do a resistance check on each end of the connector for each wire if you want to be anal about it).  If that checks out, I think you're down to swapping pieces of hardware to try and isolate the issue. You might reach out to someone like Fritz Flynn who makes a side living off of parting out RX7s and see if he's got a working but ugly hvac panel you can test with. Or even better just the guts of an HVAC panel because I know he sold me just the plastic for one years ago (which is the high demand part), so maybe he disassembles them from time to time.

Failing extra parts to swap and isolate, I suppose you could break out your meter, tie one probe to chassis ground, then start probing the rest of the wiring on the AC switch / HVAC board to see if you can find an alternative source for the AC switch output. Such a source should mirror the AC switch's output logic, so with the blower on and the AC button depressed, you'd get a ground. Any other combination would float (I.E., not ground or 12V).

Best of luck
Lane

Offline TravAZ

Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #16 on: October 22, 2018, 08:47:56 PM »
Thanks again for all of the help diagnosing my issue @halfspec.  It turns out that I had a bad AC button/switch.  I sourced a replacement HVAC control piece with board and switch.  Swapped it out my ground issue went away.  What a relief to see all of the wiring work as it should.  Nothing like having all new AC components and a fresh charge of R12.   

For any others reading this thread.  If all of your wiring looks good and you can't intercept a ground, it is possible the your AC button and/or HVAC board is bad.  The button appeared to function correctly and lit up when pressed, but it wasn't working.

Now my tach for some reason (that I just replaced) isn't working.  Let the wiring woes continue I guess...   
"You call it road rage, I call it maneuvering around assholes that don't know how to drive!"

Offline halfspec

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Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #17 on: October 23, 2018, 09:23:19 AM »
Glad you got it solved. That was an unusual problem.  :scratch:

My only advice to anyone else having trouble with their AC signal relay actuating when the AC button is pressed; please go through the troubleshooting @TravAZ and I worked through before you buy another AC switch / hvac panel. This is literally the first and only time I've seen one fail, so the probability that the problem lies elsewhere outweighs the possibility of having trouble in the hvac panel IMO.

Lane

Offline alxxx

Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #18 on: June 04, 2020, 01:39:39 PM »
I know the post is not terribly new, but I had a question regarding the stock PCM.
So i am running a standalone LS1 harness from haltech with a haltech ecu. is there any way to integrate this in with that??  :banghead:

Offline digitalsolo

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Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #19 on: June 04, 2020, 10:45:04 PM »
Yes.   Actually the Haltech wires up basically identically to the stock LS1 PCM.    You can replicate the OEM wiring from the first post and set your Haltech IO appropriately.   I have a simplified version of this layout with my Elite 2500.
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Offline alxxx

Re: Ultimate LS1 AC Control Tutorial - HalfSpec Engineering
« Reply #20 on: June 08, 2020, 10:38:44 AM »
Yes.   Actually the Haltech wires up basically identically to the stock LS1 PCM.    You can replicate the OEM wiring from the first post and set your Haltech IO appropriately.   I have a simplified version of this layout with my Elite 2500.

Bless you! I have the 950 kit with harness, ECU, and IC7 dash. I will start experimenting.