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I would suggest you go here:

https://www.f150forum.com/f38/compressor-cycling-fix-271852/

and ask if anyone there is using this on a 2011. As I am sure you know, the faster the fan speed, the higher the output temp will be.




I hooked gauges up, placed them on the windshield where I could set inside with doors shut. With A/C on max and fan on high and NO mod the vent temp is 50*. It is about 85* outside. After cooling to that temp the compressor runs 15 seconds on and 3 or 4 seconds off. This keeps the vent temp at 50*.

When I ad the resistor to the plug the compressor kicks off and stays off. My wife drove to town this morning, and had no a/c the entire trip.
 

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A little more information. I check ohms at the probe side of the plug (unplugged from ECU) while the evaporator was hot. Reading 21 (meter on 200K). Then after cooling down I checked as quick as possible. I got 123 (200K). I'm confused as I thought the warmer the probe the more resistance it had, thus the reason to ADD a resistor. This indicates just the opposite.

Also, interesting was that I left the multimeter plugged into the back of the plug while the vehicle cooled down. Of course the plug was connected to the ECU. It showed -17.5 (200K) hot and -17.8 when cooled down. But really interesting was that the compressor never cycled and the vent temp got down to 38*. When I removed the multimeter the compressor started cycling at about 6 seconds on and 3 off. The vent temp got back above 50*. The multimeter served as the mod(resistor) should have. There was no added resistor or mod in any of these tests. Does this mean anything to anybody?
 

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It means your mod cost a bit more than others.
Just leave it connected?

Hope it wasn't a fluke. (couldn't resist)

Sent from my SM-N950U using Tapatalk
 

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Tells me either your resistor is bad or not seated correctly.


A little more information. I check ohms at the probe side of the plug (unplugged from ECU) while the evaporator was hot. Reading 21 (meter on 200K). Then after cooling down I checked as quick as possible. I got 123 (200K). I'm confused as I thought the warmer the probe the more resistance it had, thus the reason to ADD a resistor. This indicates just the opposite.

Also, interesting was that I left the multimeter plugged into the back of the plug while the vehicle cooled down. Of course the plug was connected to the ECU. It showed -17.5 (200K) hot and -17.8 when cooled down. But really interesting was that the compressor never cycled and the vent temp got down to 38*. When I removed the multimeter the compressor started cycling at about 6 seconds on and 3 off. The vent temp got back above 50*. The multimeter served as the mod(resistor) should have. There was no added resistor or mod in any of these tests. Does this mean anything to anybody?
 

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Bump for the best mod ever!

Reactivated the super cooling mod today and decided to do a few tests. Tests were done in my driveway while in the shade. Recirc on, fan set to 35%'ish (to speed up cycling time).

Stock vent temps cycling:


Vent temps with 360k Ohm added:


Vent temps with 380k ohm added:

 

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So the more ohm resistance you add, the longer the cycling time/frequency, the colder the ac blows? Is this correct?

So I should start with a low Ohm resistor, say 200 and go up from there?
 

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So the more ohm resistance you add, the longer the cycling time/frequency, the colder the ac blows? Is this correct?

So I should start with a low Ohm resistor, say 200 and go up from there?
NO, you should not! Going that low will most definitely do harm and or freeze your system. look at the post just above with video. If you don't get an adjustable pot, then get a 400K, 380K and 360K. See what those do to your system. It would also be beneficial if you took a few minutes and read the big post on the other forum!

Again, do not go that low!
 

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Whoa there. I appreciate the concern. Thank you for the clarification. I did read that long thread believe it or not. I also read the thread over at f150forum. I have several resistors from 200k to 1000k ohm. My confusion is what Trev just recently posted. He uses a 360K ohm and was showing ~38 degrees. When he goes up to 380K his temp is showing ~36 degrees. So is it more ohms lower temperature? or more ohms higher temperature? From your comments I assume I should start with the highst Ohm resistor that I have, correct?
 

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Whoa there. I appreciate the concern. Thank you for the clarification. I did read that long thread believe it or not. I also read the thread over at f150forum. I have several resistors from 200k to 1000k ohm. My confusion is what Trev just recently posted. He uses a 360K ohm and was showing ~38 degrees. When he goes up to 380K his temp is showing ~36 degrees. So is it more ohms lower temperature? or more ohms higher temperature? From your comments I assume I should start with the highst Ohm resistor that I have, correct?
I am no scientist, electrician or geek! You do any of this at your own discretion and risk! All I can tell you is that these trucks are all different! Have not seen any 2 trucks act the same with the same resistor. Having said that, I would suggest a 1 meg pot switch, which you can adjust up and downward to test for your system. If you go this route, set it with a multi meter, then install. The donor truck I reference on the other forum has one and is currently dialed in around 370. Rarely does the donor truck ever use recirc or max! Remember, it may take some trial and error. You need to drive it a while for it to sync in with the resistor on the Temp Probe in the evap coil.
 

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Whoa there. I appreciate the concern. Thank you for the clarification. I did read that long thread believe it or not. I also read the thread over at f150forum. I have several resistors from 200k to 1000k ohm. My confusion is what Trev just recently posted. He uses a 360K ohm and was showing ~38 degrees. When he goes up to 380K his temp is showing ~36 degrees. So is it more ohms lower temperature? or more ohms higher temperature? From your comments I assume I should start with the highst Ohm resistor that I have, correct?
Stock i was cycling between 41-45*F

With 360K Ohm i was cycling between 35-40*F

With 380K Ohm i was cycling between 36-41*F

Those tests were done with a potentiometer and a fluke meter to verify resistance. I have since settled with using a 400k Ohm resistor.

Lower Ohms will result in colder temps. Higher Ohms will result higher temps.

I would recommend starting out with 400k ohm. I would also strongly recommend you monitor AC parameters with Forscan (not required but makes it really easy to see when the compressor is cycling on/off).

Testing Ohm range should be between 320-420k Ohms. Every vehicle is different so you will have to test and determine the best resistance for yourself.
 

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Sorry to drag up this post again but I'm interesting in trying this and have a question.

Would it work the same if you used 'wire taps' instead of shoving the wire into the connector?

I figured it would be easier to remove when not needed. I may even wire in an on-off switch.

Taps

Thanks!
 

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I like the taps that screw down and can be uninstalled easily. Can't remember what they are called. Work fantastic

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does anyone know if this mod will work on newer models or if there's a similar mod for newer models

the question was asked earlier in the thread but the only answer was that newer models don't have this issue

my 2016 is incapable of adequately cooling my supercrew cab

dealer says a/c is within specs

i park under shaded parking deck & have ceramic tint on all 4 sides but it take 15+ mins for vents to get down in the 40's

& even after that the cab never gets adequately cool


thank you
 

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I have a 2014 f150 with the 3.7. Vent temps are 60 degrees and 52 after 15 minutes of driving. Tried the resistor mod wire a 500 ohm pot and a 370 ohm resistor. In both cases when connected the compressor turns off. Is there something I am missing on this mod. Any help would be appreciated.
 
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