lanky 44 Report post Posted September 12, 2015 Hello, I have a contour dual fan setup that I'm planning to install. I will be running an independent switch system with relays (with a on/off and a high/low switch) as well as a thermostatic controller with built in relays (replaceable). Both the relays and the controller will be somewhere up front (most likely on the shroud itself) but I have a question about the grounds for them. Do I have to run the grounds all the way back to the battery or is a common chassis ground for them all okay. Want to make install look clean but obviously need everything reliable. To be clear, the independent switch/relay system is a back up, triggered by switches with Accessory power so I can sit in car and run fans for a bit to cool down without heating ignition coil up etc. The controller will be hooked up to only turn on when the ignition is on. Hate the idea of a controller burning out. My only other question is what's a good source for 12v with ignition on only? Or should I look somewhere underhood for a 12v accessory on source? Quote Share this post Link to post Share on other sites
lanky 44 Report post Posted September 12, 2015 Forgot to mention I plan on doing a 3G alternator swap for the setup as well. Cheers. Quote Share this post Link to post Share on other sites
alex 18 Report post Posted September 13, 2015 Regarding the ground, I use the radiator support as a ground. For a 12V keyed source, that is a bit tricky since the power would run all the into the ignition switch and then back out to the fan. An alternative that I have in my car is a separate fuse block that has the keyed 12V running off a relay switched by the ignition. Thus the full load of the fan would not run through the ignition switch. I hope that made sense. I am interested in answers to these questions to attempt to improve my wiring. Quote Share this post Link to post Share on other sites
lanky 44 Report post Posted September 14, 2015 By no means was I planning on the actual power coming from the keyed source. Power for the relays/controller will come from new 10ga wire from the battery. Im using relays for both the switches and the controller has them built in. What I meant was 12v (accessory keyed) and 12v (ignition keyed) for triggering the relays, not powering them. Is it generally okay to ground multiple components on one shared ground or is that a no-no? Not with mustangs necessarily, but I have heard that sometimes a shared ground can cause issues. Also, I have read that with high amperage circuits (like electric fans) that the grounds should be run all the way to the actual negative side of the battery. True? Quote Share this post Link to post Share on other sites
tonyinsandiego 37 Report post Posted September 16, 2015 I used the same exact fan but, for controls I choose a different route. I used a fan control switch for my fan low circuit and a 12v controller powered through ignition circuit that controls the high speed setup. The 12v controller was something like $5 but I used SS relays to control the fans and that's what was pricey. You can use a standard relay but I'm thinking at some point I'll try a different setup with PWM and/or PID control. That controllers for PID are pricey but I've seen them for as low as $35. Great price for PID control, I have that setup in a Toyota Tacoma with the fan control switch as a back up. The fan control switch comes on after I turn it off and it starts to heat soak. I like having it on to control the heat soak at shutdown. Of coarse, both are adjustable. Directions suck on the Chinese controller but, not to hard to figure out. http://www.ebay.com/itm/DC-12V-50-110-C-Digital-Heat-Cool-Temp-Thermostat-Temperature-Control-Switch-/400881093276?hash=item5d56600a9c http://www.amazon.com/gp/product/B000C39C6I?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00 Quote Share this post Link to post Share on other sites
