electric fan wiring with Air conditioner on

shaunditty

Shaunditty
My trucks been running great. My electric fan cycles on/off just fine and truck stays very cool even in 90+deg heat. However im tired of not being able to use my AC because its not wired for it... I see in my google searching that people wire off of the compressor clutch but that seems like a bad place to tap into since the clutch cycles.. I am thinkin of coming off the low pressure switch to feed a additional fan relay..?.?. It is what cycles the clutch, right?, so come off the power inlet side of the pressure switch and feed my fan relay makes more sense to me. Is this what you guys do and are there any other suggestions?
Thanks for any suggestions. My family will enjoy the cruising much more im sure with the AC on in this nasty heat.
 
...come off the power inlet side of the pressure switch and feed my fan relay makes more sense to me. Is this what you guys do and are there any other suggestions?
It really depends on how the rest of the fan controller is wired, and how exactly you want its behavior to change. Exactly when do you want the fan ON, and when OFF? Do you have a diagram that shows how it's wired now?


(phone app link)
 
You want the signal power to come from the switch in the cab. Give me a few hours to get home and look it up in my manual. I will get you a color code. It is one of the wires at the compressor.

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I tapped into the Black/Yellow wire at the pressure switch on the Accumulator. This wire is what triggers the AC clutch. You want the fans to come on when the compressor is running. The Black/Yellow wire is a Positive signal and you need the install a Diode to allow the signal to go to the fan circuit but not allow the fan circuit to back feed to the AC clutch.
 
My trucks been running great. My electric fan cycles on/off just fine and truck stays very cool even in 90+deg heat. However im tired of not being able to use my AC because its not wired for it... I see in my google searching that people wire off of the compressor clutch but that seems like a bad place to tap into since the clutch cycles.. I am thinkin of coming off the low pressure switch to feed a additional fan relay..?.?. It is what cycles the clutch, right?, so come off the power inlet side of the pressure switch and feed my fan relay makes more sense to me. Is this what you guys do and are there any other suggestions?
Thanks for any suggestions. My family will enjoy the cruising much more im sure with the AC on in this nasty heat.

I agree with Steve (I know mark your calendar :)) but we need to see how you have it wired now. You can trigger relays from either ground or 12v so whatever you add now is basically going to override the temp sender signal and cut the fan on. Also note, the low pressure switch is only a safeguard in case the charge is very low, it does not cycle the compressor on and off under normal operation.
 
Looks like Steve83 already posted diagrams for you. Here is the color coding
 

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I have the fan relay currently triggered by the radio circuit via a add-a-fuse. So anytime the truck is on or key is in accessory position the fan can run if sensor is closed/truck is hot. Basically just a basic circuit powered directly off the battery. I have a basic fan relay kit. Nothing fancy.
 
..the low pressure switch is only a safeguard in case the charge is very low, it does not cycle the compressor on and off under normal operation.
Yes, Ford calls it the "clutch cycling pressure switch" (as the wiring diagrams show) because, as the air in the cab becomes colder, it transfers less heat to the evaporator, causing less liquid refrigerant to boil into vapor, causing less pressure in the accumulator where that switch is.
 
I tapped into the Black/Yellow wire at the pressure switch on the Accumulator. This wire is what triggers the AC clutch. You want the fans to come on when the compressor is running. The Black/Yellow wire is a Positive signal and you need the install a Diode to allow the signal to go to the fan circuit but not allow the fan circuit to back feed to the AC clutch.
This is how I have mine. My second fan gets its signal from the pressure switch. The fan is on whenever the A/C is on.

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There is a plug over near the accumulator that has two wires going in one side of it but only one wire coming out the other side of it. One of those pins that has no wire coming out the other side is powered on when you place the air conditioning on inside the truck.

I added a wire and pin in the connector and use that to power on the relay for my fan.

d0442a724e9959797d7e23b62bf6fa47.jpg


06d0ff042514f6665890247a9bbd4fcc.jpg
 
There is a plug over near the accumulator that has two wires going in one side of it but only one wire coming out the other side of it. One of those pins that has no wire coming out the other side is powered on when you place the air conditioning on inside the truck.

I added a wire and pin in the connector and use that to power on the relay for my fan.

d0442a724e9959797d7e23b62bf6fa47.jpg


06d0ff042514f6665890247a9bbd4fcc.jpg

That’s a clean way to do it. I assume you drilled a hole on the insulator and ran another wire through.

I have my windstar fans on a switch to 2 relays. If my fans are turned off it freezes my wideband up. No idea why
 
I assume you drilled a hole on the insulator and ran another wire through.
It's soft silicone rubber - just push anything pointy through it. If it's a male terminal, it will go through the silicone & snap right into its socket (if you have the red lock out already).
 
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