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DC Pit Crew
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Discussion Starter #1 (Edited)
it's that time of year again when the mercury rises a little higher and saturday cruises are plentiful, so I thought I'd add to the plethora of recent cooling system threads.

For those who are interested in the additional space and slight HP increase of an electric fan setup, but aren't too keen on spending $400, this is what you're looking for. The two speed electric fan from the 1994 to 1998 Ford Taurus or Mercury Sable with the 3.8L engine are readily available at most junkyards for around $25 or less. I got mine for $20 so the guy wouldn't have to make any change :laughing:

It's a 16" diameter fan and I've seen a variety of CFM ratings. The general consensus is that on low speed it pulls about 2000 CFM and on high upwards of 3500 CFM :surprised Not too shabby for a junkyard fan. It's easy to see why this is such a popular conversion on lots of other cars from offroad rigs to hotrods. I'm surprised I've never seen one on a 'vette before. However, it can be a power hog on the high speed. Again, drawing on internet research the fans are said to draw up to 90 amps on startup of the high speed and up to a continuous 33 amps. A bit much for 10 gage wire and a 30 amp fuse, but you should be able to rely on the low speed and use the high speed only for extreme cases. Unfortunately I don't have an ammeter much less an oscilloscope to confirm or deny any of those numbers.

I mounted the fan to a 31" Tru-Kool radiator that I did an install thread about a year ago: cheap cooling sytem upgrade thread

I got some 1/8" by 1" aluminum and some 1/4" bolts and washers from Ace hardware. I bent the aluminum to make 4 brackets that wrap around the top and bottom flanges of the radiator and bolt to the fan shroud. Here's the fan with the brackets mounted up:


I also cut 4 slots in the shroud to get a wrench on the nyloc nut on the inside of the shroud. This makes installing/removing the fan from the radiator much easier.




So you've got the fan mounted to the radiator, now how do you make it all work? I wired mine up to use two temp switches. I put a 195* temp switch up by the radiator inlet and a 185* temp switch by the radiator exit. The 185* switch controls the low speed of the fan, the 195* switch controls the high speed. In theory, the low speed switch should kick in before the high speed switch because the water coming past the thermostat shouldn't be too much higher than 180*. Once the low speed fan has turned on it should be able to maintain enough cooling for normal conditions. The 195* high speed should be only for extreme cases. Here's the wiring diagram for such a setup:


However, after a little testing (more on that later) I've found that I'm better off just running the low speed fan. The fan runs less and still provides plenty of airflow through that big alum radiator. Here's a simplified diagram for just one switch:


Don't forget to run a ground wire from the radiator to the frame. The temp switches ground through the threads, so don't use any sealant or teflon tape on there.

I got the wire and SPST from Radio Shack and the SPDT relay and most of the crimp terminals from Autozone. If I were to do it all again I'd get actual Bosch relays online since they're pretty reasonably priced.





Initial Reaction/Evaluation:
The 195* switch needs to be at least a 205*. It would come on all the time and run way too long after the engine is shut off. Oddly enough, it would run for maybe 30 seconds after killing the engine and then shut off. But within a few minutes it would come back on and then run for 10 to 15 minutes. At this point I just disconnected the wire going to that switch and am very happy using only the lower switch. I duct taped my multimeter to the windshield and could watch it kick on and off as I drove around the neighborhood and it stayed off most of the time I was over 55 mph.

I have also noticed that the battery guage in the center console sits at +20 most of the time. I'm assuming this is an ammeter since its range is -40 to +40. If the engine is off and the fan is on, it sits at 0. But if the engine is on it sits at +20. Is this normal and I just haven't noticed it before now? Or is the alternator somehow seeing the additional current draw of the fan and overcompensating? Do I need to upgrade alternators?

I did not notice any major performance increase. It's tough to compare to 3 weeks ago when I drove it last, but I'd definitely say a clutch fan in good working order is not sucking that much HP. Don't expect to see 15 HP on the dyno because you switched to an electric fan.

All in all I'm very pleased. It cools like a champ and opens up a LOT of room in front of the engine. Also gets that finger chopper out of the way.
 

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DC Pit Crew
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Discussion Starter #6
thanks, Todd. The valve covers are desperate for a polish and the block paint isn't too great in spots, but it's getting there. Still need to do a little cleanup from when the upper hose blew off the water neck on the block :rolleyes: Hopefully the new hose clamps and new necks I had welded on the radiator will take care of some of that problem.
 

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Great install!!! I think however that your ammeter may be hooked up incorrectly. With the engine off and the fan on, it should read about -30 or so amps. Ideally, with the engine on and all the electrical systems on, AC, fan, lights, and foot on the brake, you should see about 0 on the gauge, or an even draw. But with an aftermarket fan like this or other accesories like fog lights or in the case of an old or cheap alternator, it will show a draw at idle, usually not more than 10 or 15 amps, but in any case should show a charge at above about 2000 rpms.
 

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DC Pit Crew
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Discussion Starter #9
Great install!!! I think however that your ammeter may be hooked up incorrectly. With the engine off and the fan on, it should read about -30 or so amps. Ideally, with the engine on and all the electrical systems on, AC, fan, lights, and foot on the brake, you should see about 0 on the gauge, or an even draw. But with an aftermarket fan like this or other accesories like fog lights or in the case of an old or cheap alternator, it will show a draw at idle, usually not more than 10 or 15 amps, but in any case should show a charge at above about 2000 rpms.
thanks dude, that helps. I need to do some research about how alternators know when to produce power and how much. I really think mine is running overtime. I've been noticing a whirring sound almost like a turbo or blower that I think is the alternator and occasionally I can get a whiff of that warm electronics smell. I don't want to run it too long or hard until I get that figured out. Not too keen on burning this thing to the ground...
 

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Great write up. If you can work out the kinks and prove the design I may sell my electric fans and sink the money into some other upgrades. :crazy:
 

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Fans...

With that power she is drawing would you suggest changing the alternator from the 70 amp up to 100 or 120 or would the 70 amp be strong enough...Thanx............Jerrylee///
 

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With that power she is drawing would you suggest changing the alternator from the 70 amp up to 100 or 120 or would the 70 amp be strong enough...Thanx............Jerrylee///
OK, as usual the answer is....it depends....you really need hang a voltmeter on the alt output and see wether it's happy with fans, a/c, lights, and in gear stopped if automatic, and even stereo running....with engine hot from a good run.....if that voltage drops off....you maybe want to increase the amps for sure....with all that crap running you should be able to see 14.5 voltage at the battery regardless of anything, with the engine at say 1500 rpm...I can accept 12.8 at idle....but it better jump up really quick when taking off....

I can NOT accept 12.5 volts as a typicial running voltage and having to turn off the a/c for instance, to see it rise to acceptable levels....now this is all measured at the battery terminals....
 

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DC Pit Crew
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Discussion Starter #13
I'm going out to see what the ammeter says under some different conditions and I'll measure the voltage at battery terminals while I'm at it. :thumbsup:
 

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DC Pit Crew
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Discussion Starter #14
got some good info...

Alternator is getting VERY HOT. Definitely the source of the hot electronics smell. After 15 minutes of testing with the engine at idle I could comfortably rest my hand on the steering box. I touched the alternator and damn near cooked my fingers. Not driving this thing until I get a new one. It might have something to do with the fact that it's a 42 Amp alternator :lookinup: Guess that's what you get when you have no options whatsoever.

Here's the data:


reving it up to 2500 rpm only got the voltage up to 13.27 V

Looks like now the question becomes... Chrome or plain?
 

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DC Pit Crew
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Discussion Starter #15
I recieved a few questions via PM and thought I'd post the answers here in case it helps someone else.

When i buy a fan do i want a pusher or puller?
depends on which side of the radiator you want to mount it on. If you want it on the back of the radiator (typical instll) you need a fan to pull the air through the radiator. If you want it on the front of the rad, you need a fan to push it through the radiator. The Taurus fan is obviously a puller.

Wiring, relays, switches?? what and where, or what would i ask for if i went to advanced auto.
Crash course in relays:
A relay uses a low current (control) circuit to switch a high current (power) circuit on and off. We use the temperature switches to open or close the control circuit. When the 185* temp switch is exposed to 185* coolant it switches closed and completes the control circuit. The relay sees that and closes the power circuit, sending power to the fan. The temp switch will open at 20* cooler than where it opened. Check here for more in-depth explanation: http://www.bcae1.com/relays.htm

Bosch part numbers for the relays:
40 Amp SPDT - 332 209 150
40 Amp SPST - 332 019 150
http://terminalsupplyco.com/Store/Default.aspx?CAT=EC070010

Speedway Motors part numbers for Spal Temp Switches:
195* on 175* off - 91064026-195
185* on 165* off - 91064026-185

If you look around Speedway's site or Summit you can find wiring harnesses for fairly cheap that will save your some effort of putting together the harness from scratch. I haven't seen one set up for 2 switches, but as I stated above, that didn't appear to be necessary.

What do i use for a 12 volt power source?
I ran power from the large terminal on the starter. Take a voltmeter under the car with you (if you don't have a voltmeter, get one. A cheap one from Radio Shack or Autozone will work. I have a handy automotive multimeter from Autozone that tells engine RPM, dwell, etc. Great tool for $45). Put one wire from the voltmeter to a clean spot on the frame. That's your ground, so typically use the black wire from the meter. Now put the other wire on the big starter terminal. You should see around 12 volts displayed on the meter. If not, try the other terminals until you find the right one.

Another alternative would be to get power from the power block (I think that's what it's called) mounted on the driver's side fender. Look for several heavy wires going to a couple terminals. Same procedure to find the 12V source. The power block may be a switched source, so test that one with the key in the "on" position.

Can i just wire everything up to a switch and mount it on my console??
That is one option, but it's dangerous. All you have to do is forget to switch it on and you'll cook your engine. Not something I'd want to risk. The absolute simplest alternative it to just hook the fan to a switched voltage source (only gets power when the key is in the "on" position). Then any time the engine is running the fan is running. That method is harder on your alternator and the fan as well as the rest of your electrical system. Just like any other component, these things have an expected life. So running the fan when it doesn't need to be on will burn it out sooner.

Hope that helps. Best of luck!
 

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Jason,
I don’t mean to jump in on your thread, but I like to see part numbers to go with installs. So I thought I would throw out some part number for anyone trying to do a fan install. I bought all of my items from summit it was just easier for me.

Dual relays http://store.summitracing.com/partdetail.asp?autofilter=1&part=VIA-80238&N=700+115&autoview=sku

Temp sender for the head
http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-890017&N=700+115&autoview=sku

Alternator Polished aluminum
http://store.summitracing.com/partdetail.asp?autofilter=1&part=PWM-27294&N=700+115&autoview=sku

These are items I use for my dual fan install. Every thing is working well for me, but you may want to change things to be more inline with your needs. For instance a different range temp sender, a less expensive alternator and possibly a single relay instead of dual.
Remember these are just parts that I used that work for me. I hope this helps someone :D
 

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got some good info...

Alternator is getting VERY HOT. Definitely the source of the hot electronics smell. After 15 minutes of testing with the engine at idle I could comfortably rest my hand on the steering box. I touched the alternator and damn near cooked my fingers. Not driving this thing until I get a new one. It might have something to do with the fact that it's a 42 Amp alternator :lookinup: Guess that's what you get when you have no options whatsoever.

Here's the data:


reving it up to 2500 rpm only got the voltage up to 13.27 V

Looks like now the question becomes... Chrome or plain?
I think you nailed it! Sounds like you need to get a high output alternator, maybe like the ones the cop cars and ambulances have... Also, the ammeter is definitly wired incorrectly. It should basically go between the alternator and the battery, and it will show you whether the battery is being charged by the alternator, or whether the the alternator is not able to supply enough current to the system and its being drawn directly from the battery. Again, with the engine off, ANY electrical accessories on should show a draw on an ammeter. Also, I see you a man who uses Excel like I do, For EVERYTHING! I love it,
Dude
 

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DC Pit Crew
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Discussion Starter #18
Todd, thanks for the extra info. I take it from the dual relay kit that your running a dual fan? Or is one relay unused? That alternator looks like a good option for me. I think a 100 amp alternator should be enough since the 42 amp unit was doing fine before adding the fan.

Dude, I agree that something is fishy about the ammeter readings. I would have expected a larger drop with engine off and fan on. There appears to be a slight initial offset (around 3 amps) and the needle definitely drops slightly when the key is turned to the on position. I'll be curious to see what it reads when I get the new alternator on there. It still scares me to think of how hot that old alternator was getting. That thing was hotter than a pistol after running for 5 minutes.
 

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Todd, thanks for the extra info. I take it from the dual relay kit that your running a dual fan? Or is one relay unused? That alternator looks like a good option for me. I think a 100 amp alternator should be enough since the 42 amp unit was doing fine before adding the fan.

Dude, I agree that something is fishy about the ammeter readings. I would have expected a larger drop with engine off and fan on. There appears to be a slight initial offset (around 3 amps) and the needle definitely drops slightly when the key is turned to the on position. I'll be curious to see what it reads when I get the new alternator on there. It still scares me to think of how hot that old alternator was getting. That thing was hotter than a pistol after running for 5 minutes.
Yep I’m running duals. I used both of the relays, but for 8 bucks I say get the dual set and separate them and have a spare if you only need one. On the alternator, 100 amps to me it’s plenty. I had the 42 amp and with my fans drawing a total of 40 amps constant while running, an up grade was a must. Do you know how many amps your fan pulls? From what you say about the alternator you have now being hot it sounds like you should be upgrading also.
 

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Couple of things that you might find useful. The ideal place to draw your power for your fans is at the + Power terminal of the Alternator, that way the current goes right into the fans from where it's being generated, Shortest possible run, direct, and it won't register at all on your in car ammeter. No advantage from running it from the + batt terminal, the current actually has to flow from the Alt to the batt terminal now.
The alternator senses the voltage at it's sense input to control it's output, it's voltage controlled.
To keep the fans off after you turn the ign off, disconnect the relay control voltage (+ side of the relay coils) from the 30A fuse fan power, and reconnect it to the ACC tab from the ign box. that way, when you cut off the power, you cut the relays ability to close, regardless of the state of the temp switches, and they are also off during cranking of the motor (enabled now by the ACC state). This also has the advantage of making sure that the alternator is always supplying the power to the fan, and not the Batt, keeping it from draining and leaving you stranded.
 
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