Hey guys I am hooking up an electric fan and was wondering if someone could help me in locating a key-on power source. Easiest one and under the hood if possible.
I was unable to find what I was looking for using the search feature.
The typical circuit under the hood isn't going to handle the 30 amp+ load of an electric fan. You can use the switched 12 volts from the ignition switch to control a relay, but that's about it. The main power for the fan has to come from a high current source like the battery connection on the starter solenoid. That's what HISSIN50's talking about.
If you don't have a high current alternator, you can forget about using the fan. The stock 65 amp alternator isn't big enough to run the fan and the rest of the car.
The best fan controller available today is a DC Control unit. www.dccontrol.com. Cost is about $110. Be prepared to wait 4 weeks or more to receive your controller once you have sent in your payment. The controllers are custom made in small lots and lead times can stretch out.
At the bottom are the Hayden or Imperial controllers available through Advance Discount Auto Parts and AutoZone. The non adjustable one is about $30 ( Hayden 226206) and the adjustable one is about $60 (Hayden 226204). I recommend you do a google search on Hayden and the part number for more info.
If you are good with electrical stuff (90% of the people here aren't), build your own controller. The numbers on the diagram (#86, #87, etc) refer to the numbers on the bottom of a typical automotive relay.
If you are an experienced electronics tech or electrical engineer, email me and it will send you the prototype drawings of a fan controller that is probably as good as the DC Control unit. It is a build it, troubleshoot it yourself item. I will not build or troubleshoot units, so it is not suitable for anyone who isn't really good with electronics.
Alternate placement for a temp gauge sender or temp switch/temp sensor for an electric fan. Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.
Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.
Hey thanks for your responses. It is a 1992 LX 5.0. I purchased a fan relay kit with temp. probe for 185 on 170 off. Keeps the stock gauge at halfway. I do have the 3G alternator.
Currently I hooked the main power wire to the back of the alternator. Is that ok? I am just looking for a key on so the fans will not run with the car is off.
The kit I got also has an ac over ride built in so with the compressor kicks in the fan turns on regardless of temp.
Power source for the fan should be the battery side of the starter solenoid.
The red/green wire on the ignition coil is switched 12 volts. the solid color red wires on the backside of the passenger side strut tower are also switched 12 volts. I have been told that the coolant level sensor on the overflow tank also provides switched 12 volts, but I cannot verify that.
I'd also ask about your t-stat. Unless you run a 160* stat, once your car is up to temp, the fan will run almost constantly (i.e. if you had a 180 or 195* t-stat and the fan set to turn off at 170, you'd never drop down to 170 because of the t-stat).
Hey thanks again guys. I got everything done this afternoon. jrichker, just to let you know, 2 of the 3 wires running to the coolant sensor level do provide switched 12 volts so I ended up using that.
Hissin50 currently I am running the stock thermostat and I drove it for around 30 minutes and everything worked like it should. Once I got it home I let it sit idle for another 30 minutes, the fan would kick on every 5-6 minutes and run for around 2 minutes before cutting off. I have a 185 degree thermostat to go in but I will wait a few days to see how the stock one does. I may go ahead and pick up a 160 like mentioned.
I wouldnt recommend a 160* t-stat. I was just trying to point out something that could allow you to get more miles out of your cooling fan (keeping it from running unnecessarily).
I have a guess or two as to why the fan actually cycles (in theory it should almost never because of the disparity), but I guess all that matters is that it is indeed cycling and working well for ya. Nice work.