Mod (Ret.)

On my 2007, the A/C compressor "hot" lead was grey with white stripe. I guess this was what you used initially, but it caused your fan to cycle on and off whenever the A/C clutch operated as you stated in your ealier post. The purple wire is the dash A/C switch (green light). Good selection to use as a trigger so that the fan does not go "on/off" constantly!

dhonnoll

awesome. Can't see pics yet but posting so I can find this violet wire and won't forget it. This is what I want to do. Have the fan come on with the AC, compressor or not.

Hongstertruck

If you want electric fan get the 2010 F150 one, it has dual fans and fit right on your existing radiator with some small modifications.

And, if you go with Painless controller it's a match that can't be beat, the painless controller uses PWM to ramp the motor up to 50% then it will go higher depends on the cooling temp.
It also has A/C on feature but the best is it has VSS (vehicle speed sensor), you can tell the fan to cut off at a certain vehicle speed.

Blown Ford

Here's my thread on 2010 F150 Motorcraft fans. Less expensive then this setup, more cooling power, and lots more room under the hood. Didn't have to upgrade the altenator either. Nearly 4 years with this setup. Keeps my stock motor pushing over 500rwhp cooled just fine.
Nice job making the GT500 fan work though.
https://www.f150forum.com/f4/motorcraft-efans-04-08-pics-vid-114646/

dhonnoll

Part 2 of the write up? Looking to do this with a Lincoln Mark VII I took yesterday and Volvo 2 speed controller. Still need to find a portátil and say to mount a BMW 2 temp switch though.

gmachinz

Hey guys! Yes, that's my 3-speed resistor controlled relay harness. I make several versions of it-including one for the 2010-up F150 dual fans. The nice thing about it is the flexibility to easily access any part of the kit in the event (unlikely at that BTW) of a failure since it uses 5-pin Bosch relays and a commonly available resistor board. The relays I use in these kits are rated @ 250,000 switching cycles at full load. This members GT500 fan kit uses (2) 40A switching relays and (2) 50A load relays. I'm happy to answer any questions anybody may have!

jb2012

sub'd

gmachinz

My current F150 dual fan kit uses (2) 50A switching relays and (2) 75A load relays. The 75A load relays are rated @ 75A for 250,000 switching cycles but can also handle 100A @ 100,000 switching cycles as well. The biggest issue with these HD OEM style fan(s) is the start up (or in-rush) current, which can be as high as 175A for the first several milliseconds. For this reason, a single relay alone won't last long a especially a cheap version of a 70A+ Chinese relay with lower grade contact material-the sudden spiking off/on every time the fan is triggered @ 100% fan speed can literally arc the contacts together to the point they either fail to release (continuous run-on) or they burn out the contacts completely.

Where my harness differs is that when low speed circuit when activated either by a switch or an ecm ground trigger, the current is immediately forced through a series of fixed value resistors effectively running the fan(s) @ 9V or, "low speed".

When the medium speed is triggered again by either a switch or ecm, a series resistor drops out-effectively dropping some resistance and raising the voltage to 12V or "medium speed".

Finally, if AC is triggered (can be wired to AC clutch or through a trinary switch) then all resistors are bypassed and high speed is achieved (14V+). So, its a series of fan speeds all designed to maximize the fans performance while drastically reducing voltage spiking and extending the life of the fan motor(s).

This kit uses HD commercial grade relays although in a pinch you can use standard relays (load relays are screw down terminal type) but keep in mind this particular F150 fan can pull as much as 60A full speed-so I have chosen my components carefully to support it. No worries with soon to be obsolete controllers, 4th design PWM's....blah blah....I've been down that road-a very limited number work well but relays are a tried and true system and I wouldn't hesitate to use them.

If anybody has questions about their particular fan setup-lemme know! I've been building kits for Mark VIII fans, RF24 2-speed T-Bird fans, Crown Vic 2-speed fans, Mustang GT and F150 fans, ect....imo Motorcraft makes the most robust fans period!

dhonnoll

I have a question. I recently got a 3 wire Lincoln MarkVii fan ( I believe that makes it a 2 speed right? So I also got a Volvo relay style controller because they are supposed to support high amp loads. What size breaker or fuse should I fee that setup with? is 50amp not enough on that 2 speed?

dhonnoll

Another question. To add the relay to turn the fan on when AC is on (regardless of compress or on/off state) I take it you need to take the instrument cluster out? Would it not be easier and just as accessable to remove the radio? How hard is it to remove the instrument cluster in these trucks?