Electric Fan.....

Sean · April 21, 2004, 06:13:17 PM

I put a 16" 2100cfm electric fan in my f100 this afternoon. Cruising around town and out on the highway, it runs about 180 degrees, which is normal.

I got out on my favorite blacktop, found a tar patch, and did a big burnout followed by a full throttle blast for roughly 1/4 mile and the temperature got up to about 200 degrees. The temperature dropped down to normal pretty quickly, and stayed that way until I did another WOT pass. Same thing, about 200 degrees.

Is this just because the fan runs at a constant speed instead of accelerating with the motor, or do I not have a big enough fan? I idled through traffic in town for about 20 minutes and never budged over 180, it only does it when I am running the crap out of it.

It didn't do this with the "Race Fan" (non-flex) that I was running before, but the thing made so much noise going down the highway I couldn't hear my phone, or my stereo over the whine.

Sean · April 21, 2004, 06:24:01 PM

And another thing.....

I bought a perma-cool thermal switch to operate this fan. Shoddy looking little thing that zip ties to your upper radiator hose and is supposed to turn the fan on when the hose reaches 170 degrees. Turned out to be a $20 piece of crap...

First, the thing kept trying to twist over sideways after the zip-tie was tightened, then after I finally got it to stay where it was supposed to, it didn't work anyway. I let my truck get to a little over 220 degrees before I gave up on it and just wired the fan to the ignition switch.

WZ JUNK · April 21, 2004, 06:35:01 PM

Wire in a 30 amp relay to operate the fan. Install a fan temperature sensor in your block. I use one from a Chrysler mini van that triggers at 190 degrees. Use the sensor to trigger the relay and fuse the relay for 30 amps on the fan side. Wire the system so that the relay has power when the ignition is on. Do not worry about the temperature if the car does not boil over.

Sean · April 21, 2004, 07:16:17 PM

Quote from: "WZ JUNK"Install a fan temperature sensor in your block. Use the sensor to trigger the relay and fuse the relay for 30 amps on the fan side.

I have a 30 amp inline fuse on it now. The instructions said to use it on the "ground" side. I had never heard of doing it that way, but I guess it works the same either way.

Is there an advantage to having it running off a temperature switch instead of full time? The fuse panel in my f100 only has 3 fuses in it, but it had two unused spade terminals also. One is hot all the time, and the other is only hot when the ignition is on. Right now I have the fan hooked to the one thats only hot when the ignition is on.

Switching to the electric fan made a slight, but noticeable difference in power. I wonder how much horsepower that solid hubbed fan was eating up....

SKR8PN · April 21, 2004, 07:42:16 PM

The advantage of running your fan thru a temp sensor,and a relay,is you will not burn out the fan motor NEARLY as quick as you will running it all the time. Do you have a thermostat in the engine? if so,what size?
One other idea,is to rev the engine while it is in neutral/park,and watch the upper rad hose to be sure it not collapsing at higher engine speeds.

WZ JUNK · April 21, 2004, 08:07:55 PM

Quote from: "Sean"
Quote from: "WZ JUNK"Install a fan temperature sensor in your block. Use the sensor to trigger the relay and fuse the relay for 30 amps on the fan side.

I have a 30 amp inline fuse on it now. The instructions said to use it on the "ground" side. I had never heard of doing it that way, but I guess it works the same either way.

Is there an advantage to having it running off a temperature switch instead of full time? The fuse panel in my f100 only has 3 fuses in it, but it had two unused spade terminals also. One is hot all the time, and the other is only hot when the ignition is on. Right now I have the fan hooked to the one thats only hot when the ignition is on.

Go to this site http://www.vintageair.com/download/TrinarySafety(pt24678-VUS)Wiring.pdf Look at the diagram but do not pay any attention to the side that hooks to the trinary switch just the wiring for the fan. You can start another circuit by adding a wire and fuse off your main hot wire at the alternator / starter electrical connection to power the fan. Use the key controled hot wire to send power to trigger the relay. That way the fan only runs with the key on.

Sean · April 21, 2004, 08:46:51 PM

Its got a 190 degree thermostat in it and it ran around 190-200 until I put the Aluminum radiator in it. It dropped to 180 after that and usually stays there. Being one of the newer 350's it is probably supposed to run around 200 anyway...

Thanks for the link WzJunk, that diagram is clear enough for me to follow. I don't know anything about relays though. Is that something you get at a parts house, or do I need to order it from somewhere?

river1 · April 21, 2004, 08:54:58 PM

an addition to sean's question.

are all relays the same other then amp size?

later jim

WZ JUNK · April 21, 2004, 09:11:12 PM

Quote from: "Sean"Its got a 190 degree thermostat in it and it ran around 190-200 until I put the Aluminum radiator in it. It dropped to 180 after that and usually stays there. Being one of the newer 350's it is probably supposed to run around 200 anyway...

Thanks for the link WzJunk, that diagram clear enough for me to follow. I don't know anything about relays though. Is that something you get at a parts house, or do I need to order it from somewhere?

I usually pick up some relays when I am at a bigger show or I stop by Haywire which is just 15 minuets away. I buy the relay with a plug in socket as it makes changing out the relay a whole lot easier and they usually have a mounting tab, and a short pigtail harness attached. You can buy them at larger auto parts stores but they usually cost more, so I keep some on hand. A lot of 4 wheeler guys use a relay to turn on their fog lights.

I hope Skip is watching this post as I would like to know more about the rating of relays. I usually buy the 30 amp ones. I figured the difference was just in their current carrying capacity and so I buy the larger ones. The idea behind a relay is that you can use a small amount of current to trigger a device that requires a larger amount and therefore do it more safely or without the use of a larger switch.

Sean · April 21, 2004, 09:30:07 PM

I don't need 10 of them, but does this look like what I need to be looking for?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=14934&item=3092128092&rd=1

Sean · April 21, 2004, 09:38:00 PM

I found a Dutch auction for 30 amp relays with plugs. I went ahead and ordered one of them, it looks like there are 19 of them left on this auction if any of you are interested....

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2474924327&category=38655

enjenjo · April 22, 2004, 01:47:29 AM

Those relays will work fine. I use them on everything, including for horn relays. I picked some up the ither day for $1 apeice, new. List price on them is up to $26 depending on where you buy them. Common brands are Bosch, Brumfield and Potter, or Seimens Allis. There are several variations, but they are all wired pretty much the same. There are some with a diode built in to control current flow.

I use them for fan relays, to control door solenoids, to control vacuum switches for high gear ignition retard, horn relays, to isolate the alternator exciter on race cars, for pulse wipers, and about everything else you can imagine.

Most late model cars 90 or newer have several of them in the wiring, I have never found a bad one in a salvage yard.

Ed ke6bnl · April 22, 2004, 07:37:48 AM

Quote from: "Sean"I found a Dutch auction for 30 amp relays with plugs. I went ahead and ordered one of them, it looks like there are 19 of them left on this auction if any of you are interested....

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2474924327&category=38655

one thing nice about the pigtail for the relay is that they usually have a provision to slide them together and you can have a nice clean group of relays grouped together. I just installed one like that for my 327 chevy starter so the ignition switch has the load removed from it and a large amp source is used to energize the starter soenoid. I purchase mine from all electronics inVan Nuys calif. I believe they sell through a web site and are very reasonable. I have them for my dual spall fans and the headlights, most all vehicle use them to fire off the HORN. also. Ed ke6bnl

rumrumm · April 22, 2004, 08:29:47 AM

If you want a very good sensing device, check out Centech's unit to actuate the electric fan. Very, very slick. And it will work with either analog or digital gauges. It is about the size of a package of cigarettes so you can mount it under your dash without any problems.

Mikej · April 22, 2004, 10:07:44 AM

I have an adjustable thermostat on mine. I think I bought it from Yogi's. It has a remote bulb sensor. It was suppose to be installed in the upper radiator hose but I slid it between the fins, at the top of the radiator. It was a kit and included the relay. Works great.
The advantage of the thermostat is that the fan does not run going down the highway.
I have a Griffon radiator that has a bung in the lower tank for a thermostat. It does not work worth a darn.