This sounds very interesting. Could you share just a little more info as to how you did this? I could only assume that the controller has a dual terminal(high/low) setup to enable such a thing. Thanks.
Single stage controller. There is a wire under the dash, don't remember the color, that only has power when the key is in the RUN position. I use that to energize a relay that has battery + at the common terminal, the high speed at the NO terminal, and the low fan speed winding on the NC terminal. This is a 30 amp relay that can power the low speed directly. If the high speed is needed, those contacts in turn energize a 75 amp relay that powers the high speed windings. Something Frank mentioned earlier, and I should have been more detailed in my reply at that time, about it being much easier to get to high speed if the fan is first running on low is true. When my fan comes on right to high speed there is about a 70 amp surge. I had to add RC snubber circuits to protect the relay contacts and a pair of big diodes right on the fan wires to dissipate the back EMF of the windings. With a carb on my engine I had almost a 200 rpm drop at idle when the fan turned on. I'm hoping the FiTech EFI will self-compensate for that. The Volvo setup Frank has works very well, I just did mine this way because I had all of the parts laying around and used what I had for free.
Forgot to mention, future plan calls for a bypass toggle switch that I can use to run low speed continuously in case my controller craps out.
My homemade controller. The relay on the left has since been changed out for different style relay and the snubbers were added after this was taken.
this does make it a little simpler. to fan...green to low(1)...red to high(2) ...brown and green to temp sensors...big red to 30 amp relay switched on 12V.
Frank, Did you pull this at the bone yard? If someone were to buy it new, how would you obtain the connectors? Around here, the boneyards are not filled with Volvo's.
Dakota Digital makes a fan controller that allows you to set the on/off temperature points, triggers the fan when the AC comes on and allows the fan to run after shut down to drop under hood temps. http://www.dakotadigital.com/index....t_id=852/category_id=403/mode=prod/prd852.htm Leash makes a nice relay but it looks like they will be back ordered on them. There is a picture of it in my post. http://leashelectronics.com/main.sc Micah
Good question and you're way ahead of me there. I was just happy to copy the thread and pic's into my "cooling system" folder. lol I would think that if you can't find one to hack out of the boneyard car I'm thinking that dealers would carry/order them for you. Not too sure about Volvo's but many OEM connectors are replaceable separate of the wires.
Micah, a lot of them will do that these days but will they ones you mentioned also allow the fans to be high/low'd too? The simpler way that I've learned to hook them up to be less intrusive(voltage spikes and noise) is with 2 separate relays(one for each fan). Then the adjustable temp relays would be set at slightly different temps from one another to allow only one fan to run after the coolant temp spikes from shutdown. It works seamlessly but the main issue that I have with that setup is that I typically always run dual fans and they must be staggered diagonally to fit the rad's core and it leads to some cores not getting the benefit of cooling assist. It works great but I would rather mimic the high/low relay as seems to be going on here so I get cooling across all cores but just at lower airflow speeds.
Roberts, There is a link on the site to download the instruction manual. It does control a two speed fan and you can set the temperatures for the high fan to come on and off. They supply one relay. I went with the Leash set up because it is contained in one unit and has fuses. I have it mounted in the right fender. Micah
Thanks much Micah. Very helpful.. will check links out later on. Probably should get out into the garage to actually get the motor built first so any of this is even relevant and useful info.
Nothing wrong with planning ahead. I was ordering things and buying parts months before I disassembled the car. The controller was an easy install with EFI. Everything was right there to tap into at the computer. I just had to run two wires from the cntroller in passenger compartment to the two relays near the fan. One thing about the Taurus fan, it moves a hell of a lot of air. It is surprising. On shutdown when the fan is still running, I can feel the hot air blowing out from under the car all the way back to the rear end. Micah
yep.. OEM stuff kicks ass of most the aftermarket stuff. Much tougher standards to adhere to. I've been told by engineers that some of these shrouds are literally computer designed to improve efficiency before the fans, many of which share motor/chassis from other models, are even added to turn them into mini wind-tunnels. I myself was most interested in the relay setups you guys were using here and probably won't even try to run my cars stock radiator due to power potential/heat output of my particular combo. With only slight engine setback plans initially, I'm looking towards an economy(even OEM) full aluminum cross-flow setup vs these old model T style down-flow deals. Might have to hack it up a bit in the interim by making some temp brackets to stuff it all in there but that's the least of my worries in the scheme of building a custom car. lol Thanks again, Greg
Tim has the Dakota Digital controller on his car... the harness is bone yard...between Tim and I we have close to 5 setups for the Volvo relay...
