Simplest way for single speed fan and retain ac function?
07-02-2015, 08:26 PM
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Simplest way for single speed fan and retain ac function? Can someone provide me detail on the simplest way to retain ac functionality through the LS computer but convert to a single speed fan setup?
I'll be wiring the GM ac trinary switch into the swapped vehicle. I understand this is mandatory for the ac to function properly through the GM/LS computer.
The swapped vehicle will be using its factory single speed radiator fan and factory single speed ac condenser fan. Like most manufacturers, the radiator fan and ac condenser fan both run when you engage the ac compressor.
I'll be using the LS computer to power the swapped vehicles factory relays which will in turn power up the fan(s).
Can I just wire up my LS harness to the low speed fan control only? Then disable high speed in tuning software?
Or wire up only the high speed and disable the low speed?
What's the best way to achieve OE like functionality out of what I'm trying to do?
I'll be wiring the GM ac trinary switch into the swapped vehicle. I understand this is mandatory for the ac to function properly through the GM/LS computer.
The swapped vehicle will be using its factory single speed radiator fan and factory single speed ac condenser fan. Like most manufacturers, the radiator fan and ac condenser fan both run when you engage the ac compressor.
I'll be using the LS computer to power the swapped vehicles factory relays which will in turn power up the fan(s).
Can I just wire up my LS harness to the low speed fan control only? Then disable high speed in tuning software?
Or wire up only the high speed and disable the low speed?
What's the best way to achieve OE like functionality out of what I'm trying to do?
07-02-2015, 09:04 PM
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Someone suggested running C100-J (low speed fan control) to my radiator fan and C100-H (high speed fan control) to the ac condenser fan.
Would this work?
After digging into the swapped cars wiring diagram more, I noticed, in OE configuration, BOTH fans in any fan situation even though they each have their own relay.
What I mean is that if the fan switch engages due to engine temp, it turns on BOTH fans.
If the ac is turned on, again, BOTH fans turn on.
There's never a fan situation where only 1 fan is running. It's both or nothing.
I would like to mimic this setup since I will be using the original fans/radiator in the swapped vehicle; the oe manufacturer certainly did it for a reason.
My problem is I don't know enough about the LS PCM functions.
If the low speed fan stays on when the high speed fan turns on, I guess the above suggestion would work. But if not, I'll need to figure something else out.
I need some help here - LS wiring diagrams don't tell me anything about when/how the pcm controls each fan and to what extent.
I need a way for the LS PCM to turn on both of my factory fans at the same time whether it be due to engine temps or due to turning the ac on.
Thanks in advance!
Would this work?
After digging into the swapped cars wiring diagram more, I noticed, in OE configuration, BOTH fans in any fan situation even though they each have their own relay.
What I mean is that if the fan switch engages due to engine temp, it turns on BOTH fans.
If the ac is turned on, again, BOTH fans turn on.
There's never a fan situation where only 1 fan is running. It's both or nothing.
I would like to mimic this setup since I will be using the original fans/radiator in the swapped vehicle; the oe manufacturer certainly did it for a reason.
My problem is I don't know enough about the LS PCM functions.
If the low speed fan stays on when the high speed fan turns on, I guess the above suggestion would work. But if not, I'll need to figure something else out.
I need some help here - LS wiring diagrams don't tell me anything about when/how the pcm controls each fan and to what extent.
I need a way for the LS PCM to turn on both of my factory fans at the same time whether it be due to engine temps or due to turning the ac on.
Thanks in advance!
Last edited by jonathan_ed3; 07-02-2015 at 09:10 PM.
07-03-2015, 09:39 AM
#3
If you want both fans to operate at the same time then just wire both of them to the low speed fan output and tell the PCM that you only have one fan. Personally I'd use the 3 relay setup to get the fans to run on low ( half ) speed and high ( full ) speed. You need to remember the PCM output controls the fan relay by grounding it.
07-03-2015, 09:55 AM
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Would selecting one fan in the PCM work? After posting this thread last night I found some more detailed info regarding the fans here http://www.thirdgen.org/forums/ltx-l...-fan-temp.html
It looks like just hooking the low speed up results in situations where the fan may not run when needed.
If I tell the PCM there's only one fan, will it run in all situations? Or would I be limiting myself to just certain situations?
Someone suggested in that thread to run both the high and low speed PCM ground outputs to the single fan lead. I guess this would work in theory. He says he's been running this way for 3 years. Are there any pcm ramifications doing this? This would essentially be sending a ground signal to the high speed PCM pin while the PCM is only trying to run the low speed and vice versa.
Can you provide any detail on making the fans run at high and low speed while only having single speed fans? I'm not sure I understand how to wire the relays to make that happen.
It looks like just hooking the low speed up results in situations where the fan may not run when needed.
If I tell the PCM there's only one fan, will it run in all situations? Or would I be limiting myself to just certain situations?
Someone suggested in that thread to run both the high and low speed PCM ground outputs to the single fan lead. I guess this would work in theory. He says he's been running this way for 3 years. Are there any pcm ramifications doing this? This would essentially be sending a ground signal to the high speed PCM pin while the PCM is only trying to run the low speed and vice versa.
Can you provide any detail on making the fans run at high and low speed while only having single speed fans? I'm not sure I understand how to wire the relays to make that happen.
07-03-2015, 01:00 PM
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On my rx7 ls1 swap, we did it this way. But I didn't have ac in the car. I'm also in TX and even in July and August I never had a cooling issue on that car using only a universal Hayden electric single speed fan.
On my new swap, we're keeping ac and wiring it through the ls1 3 pin pressure switch.
Do you have any insight on how the GM ecu would process fan controls with ac engaged but with fan 2 deleted?
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07-03-2015, 06:41 PM
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I appreciate your help so far.
I've thought about doing that, but my concern is how do I ensure the ac condenser fan runs when needed to provide proper airflow across the condenser (low speed conditions, sitting in traffic etc) as opposed to just running while the ac clutch is engaged?
I've thought about doing that, but my concern is how do I ensure the ac condenser fan runs when needed to provide proper airflow across the condenser (low speed conditions, sitting in traffic etc) as opposed to just running while the ac clutch is engaged?
07-03-2015, 08:30 PM
#9
Trailblazer EXT's with 5.3's use single electric fan control and it works with AC with no issues. They need the second fan output to operate the recirc door. They use a unique electronic clutch contril of a single mechanicly driven fan with speed feedback to the PCM.
