2010-up Mustang GT fans a worthy successor to the Mark VIII

[H2Ogbodies]

I've been building a lot of these lately-the shroud has provisions for installing a coolant overflow but overall the fan is pretty sanitary in appearance. It is slightly larger overall compared to the Mark VIII of lore....24x19x6 inches roughly. Here I have my 3 speed harness installed on one....if you have a chance to try one out you won't regret it-very powerful fan! Attachment 99214

[69cutlassrkt]

Is that 4 relays at the bottom? What are they all for?

[H2Ogbodies]

I wire my fans to vary in speeds based on dropping in/out of a series of fixed resistors-which lead provides power to the fan is based on which relays are activated via a temp switch. For this kit to perform as designed, it requires only 2 temp switches or ground triggers.

So, you have a low temp, medium temp and a high speed override for AC use or as a manual override. Those make up 3 of the relays and the 4th provides a path to ground for the fan with the IGN on using a 10ga lead. The resistor board is a common GM blower motor resistor found in any parts store and the 5 pin relays are also easy to source. The ones I use are commercial ones with a switching cycle of 250,000 so they'll likely rarely wear out.

With this setup, not only can you convert ANY fan or dual fan setup to operate in 3 speed mode but you can easily get replacement parts and for installation there are only 6 leads to run. I don't think there exists a relay based fan kit that can beat this one overall.

I got tired of faulty "controllers" so this was my solution-I have zero problems with this arrangement so far.

[H2Ogbodies]

I wanted to add that on factory Mustangs these fans are protected with a 60A MAXI style fuse and after testing the amp draw on another kit I just assembled with my 3-speed harness, I observed 13, 22 and 31 amp draws for each respective speed. I can safely say the result of having a series of resistors varying the speeds that it prevents the fan from initiating high start-up current and that changing from a higher speed to lower, there is virtually no voltage spiking either-this is verified with my Fluke multimeter. I plan to test my harness on a 6000 CFM Motorcraft dual 14" fan assembly and see how well it holds up-this should be the highest amp draw fan assembly in production-at least to my knowledge.