how can i make the computer turn the fan on for the AC?
how can i make the computer turn the fan on for the AC? ok, i have a 69 camaro with a vintage air ac unit. I need the high speed fan to come on when the ac unit is running. what pin on the computer can get this done? will it need a 12v or a ground signal?
the computer is a 99 model LS1
thanks
the computer is a 99 model LS1
thanks
Pin 43, connector C2 sends a ground signal to the compressor relay. You might be able to tie into that one, but I don't know for sure if it would work or not. Look at the very first schematic in this post.
https://ls1tech.com/forums/conversions-swaps/936409-99-02-schematics.html
https://ls1tech.com/forums/conversions-swaps/936409-99-02-schematics.html
How do you have your fans wired?
one of the turn on conditions for high speed fans is A/C system pressure. When you run the A/C, the PCM will trigger the high speed Fans mode as the A/C pressure rises meaning the second fan will only come on as the PCM sees fit based on the A/C pressure and other conditions as well such as engine temp.
I Cant help much if you want the second fan to always be on as long as the A/C switch is on.
one of the turn on conditions for high speed fans is A/C system pressure. When you run the A/C, the PCM will trigger the high speed Fans mode as the A/C pressure rises meaning the second fan will only come on as the PCM sees fit based on the A/C pressure and other conditions as well such as engine temp.
I Cant help much if you want the second fan to always be on as long as the A/C switch is on.
Ther is no way to accomplish that with the PCM. As stated the PCM only runs one fan full time when the A/C is running. IT's gets the signal through the A/C request wire. Problem is it won't work unless everything else for the A/C is operational.
I would probably just use the power to the compressor to trigger the relays getting you high speed.
Re'
I would probably just use the power to the compressor to trigger the relays getting you high speed.
Re'
On The Tree
Joined: Jul 2004
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From: Stockholm, Sweden
I have it working in my car as it is supposed to do in a factory LS1 car.
To get it to work correctly you have incorporate the LS1 AC Highpressure switch in your Vintage Air system. This switch is an important part of the AC control system.
Then it is just a matter of connecting the Vintage Air controller that turns on the AC to the AC request for the PCM. And then the PCM ground signal to the compressor.
There are wiring diagrams here in the FAQ onhow this should be done.
But as said previously, when AC is on it is only highspeed on the fans.
Jan
To get it to work correctly you have incorporate the LS1 AC Highpressure switch in your Vintage Air system. This switch is an important part of the AC control system.
Then it is just a matter of connecting the Vintage Air controller that turns on the AC to the AC request for the PCM. And then the PCM ground signal to the compressor.
There are wiring diagrams here in the FAQ onhow this should be done.
But as said previously, when AC is on it is only highspeed on the fans.
Jan
Last edited by jannes_z-28; Jul 31, 2008 at 04:49 AM. Reason: Added image
Teching In
Joined: Feb 2007
Posts: 5
Likes: 0
It is very simple once you install the oem pressure sensor. Only 5 wires, However on my 2000 vette pcm/fuseblock, it reqiured a 12v on the ac request wire and not a ground. The factory schematic was a little misleading, but does need 12v in order to work. Not sure if other pcm's reqiure the same.
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The only thing I have connected to my '99 LS1 PCM AC-wise is the AC refrigerant pressure sensor, and my fans come on low at some PSI and then kick to high as at some higher PSI.
Here's a post with the text from the '98 Fbody manual:
https://ls1tech.com/forums/showpost....1&postcount=35
Here's a post with the text from the '98 Fbody manual:
https://ls1tech.com/forums/showpost....1&postcount=35
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