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2005 gmc envoy_sle_xuv
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419 Posts
yahyah, all fans only need a power and a ground to really work, its how its controlled is the issue. With either a fan controller, or using the PWM control on the ECU and triggering it with a tuning software in the code.
 

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2002 chevy trailblazer_lt_ext
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78 Posts
I have a Lincoln Mark VIII fan in my TB. I was using a dccontrol.com 2speed controller for it. I'm not sure if it was the controller or what but my 30 amp fuse kept blowing and my engine got pretty hot a couple of times. I've had to replace my heater core valve because it melted the plastic rings inside. So I got rid of the controller and went with something I knew would work. A simple relay and fuse. Used my headlights to activate the relay and it's been working great.
 

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2004 chevy trailblazer_lt
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826 Posts
I have a Lincoln Mark VIII fan in my TB. I was using a dccontrol.com 2speed controller for it. I'm not sure if it was the controller or what but my 30 amp fuse kept blowing and my engine got pretty hot a couple of times. I've had to replace my heater core valve because it melted the plastic rings inside. So I got rid of the controller and went with something I knew would work. A simple relay and fuse. Used my headlights to activate the relay and it's been working great.
Is there still 2 speeds or does it just come on full speed now. witch is OK with air conditioning ...
 

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2002 chevy trailblazer_ls
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3 Posts
I have a Lincoln Mark VIII fan in my TB. I was using a dccontrol.com 2speed controller for it. I'm not sure if it was the controller or what but my 30 amp fuse kept blowing and my engine got pretty hot a couple of times. I've had to replace my heater core valve because it melted the plastic rings inside. So I got rid of the controller and went with something I knew would work. A simple relay and fuse. Used my headlights to activate the relay and it's been working great.
You need a biiger fuse than 30amps to run a Mark VIII fan. I would install a 50amp fuse in there with the correct size wire. That fan draws a TON of amps espically at startup, over 100amps. Also make sure you charging system is up to task to supply the correct voaltge to it.
 

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2002 chevy trailblazer_ls
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3 Posts
If you keep the fan maybe around 90% max, it will still pull a ton of air, but not tax the electrical system too badly.

The thing you don't want to do with these Mk VIII fans is have them turn on full speed from a stop, as I have tested it, and it will spike at 87A for a moment, before settling in at around 38A (these amperages were tested at about 12.4VDC, they may in fact be less at 14+ VDC, but I haven't tested it at those voltages at this time).
In a DC system the current goes up as the voltage increases. The Mark VIII fan will draw over 100amps on startup with higher running voltages, 13-14v.

In an AC system the voltage will drop at voltage increases.
 

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2008 chevy trailblazer_ss_3ss
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22 Posts
In a DC system the current goes up as the voltage increases. The Mark VIII fan will draw over 100amps on startup with higher running voltages, 13-14v.

In an AC system the voltage will drop at voltage increases.
Are you sure the current increases as voltage rises? If so, then increasing voltage, and thereby current, increases power exponentially, correct?

I only took one class in electrical engineering, but remember Ohm's Law, and KCL and KVL, but that doesn't mean I mastered them ;) (I'm an ME, not EE).
 

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2002 chevy trailblazer_lt_ext
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78 Posts
Just an update: I finally got around to removing my fan and making cut outs. I made square/triangle cut outs everywhere I could on the shroud to let air pass freely through the radiator, so it's not all forced through the fan. To be honest I have seen a drop in my temp and am very pleased with it. I read a reply from someone about if we really wanted to cool our engines that we shouldn't worry so much about an e-fan but get a bigger radiator. What about something like this;
It's a triple pass, two row aluminium radiator. Just an idea
 

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2004 gmc envoy_sle_xl
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397 Posts
How hard is it to find someone who would know how to tune the controls for the efans to come on at operating temps? Can pcm4less do that? i was going to have them reflash mine for different settings, and also blocking the code when removing the fan clutch, but i don't want to spend more money on a controller.
 

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2008 chevy trailblazer_ss_3ss
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22 Posts
How hard is it to find someone who would know how to tune the controls for the efans to come on at operating temps? Can pcm4less do that? i was going to have them reflash mine for different settings, and also blocking the code when removing the fan clutch, but i don't want to spend more money on a controller.
GM's operating system will only allow it down to 192F. You need to go to an aftermarket fan controller to get it lower.
 

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1,354 Posts
How hard is it to find someone who would know how to tune the controls for the efans to come on at operating temps? Can pcm4less do that? i was going to have them reflash mine for different settings, and also blocking the code when removing the fan clutch, but i don't want to spend more money on a controller.

*edit* i read your post wrong. No you will need a controller to do that
 

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2006 chevy trailblazer_ls
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389 Posts
How hard is it to find someone who would know how to tune the controls for the efans to come on at operating temps? Can pcm4less do that? i was going to have them reflash mine for different settings, and also blocking the code when removing the fan clutch, but i don't want to spend more money on a controller.
IIRC only 2008 or later PCMs can be tuned to control fan relays directly.
 

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2004 gmc envoy_sle_xl
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397 Posts
Ok so I do need a "controller?" Is it just a separate mounted module, or some kind of interior controller that I use manually at my own discretion according to the temperature? I'd rather have something that just adjusted it automatically. So our PCM's don't have much say in regulating the temperature, and the only mod I need to do on it is just have it flashed to block out the code it would throw upon removing the fan clutch?
 

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2006 chevy trailblazer_ls
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389 Posts
Ok so I do need a "controller?" Is it just a separate mounted module, or some kind of interior controller that I use manually at my own discretion according to the temperature? I'd rather have something that just adjusted it automatically.
You can do it either way. DCControls and Flex-a-lite make controllers that will turn on your fans based on temperature. There are also less sophisticated temperature controlled relays. Some people wire them to come on anytime the vehicle is on or you could wire a switch in the cabin so you control the fan at your discretion.

So our PCM's don't have much say in regulating the temperature, and the only mod I need to do on it is just have it flashed to block out the code it would throw upon removing the fan clutch?
Yep, you need a tune to remove the clutch-related codes and then just an alternative way to control the fan(s).
 

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2002 chevy trailblazer_lt_ext
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78 Posts
Anyone that has or wanting an efan and plans on driving in deep water; it is suggested that you wire in a manual switch so you can turn of the fan at your discretion. :m2:
 

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2004 gmc envoy_sle_xl
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397 Posts
Ok so an LS1 efan set, and that mounting kit from pcm4less, PLUS a module that controls when the fans come on, or is that included in the pcm4less kit?
 

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2008 chevy trailblazer_ss_3ss
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22 Posts
Ok so an LS1 efan set, and that mounting kit from pcm4less, PLUS a module that controls when the fans come on, or is that included in the pcm4less kit?
Everything is included, even the ECM patch.

Just call them and talk to Alvin, Kelly, or Marshall.
 

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2006 chevy trailblazer_lt
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