I recently got rid of the stock plastic fan (which cracks all the time) and the fan clutch. To replace it, I put on an electric fan from a 93 Taurus in the junkyard.

For the control, I tapped the output of the coolant temperature switch on the intake manifold and built my own closed loop current source for the fan to keep it at about 195 degrees F. Doing this will vary the fan speed continuously, instead of going the bang-on bang-off route of the usual aftermarket control boxes.

To keep up efficiency, I also put in a pressure switch on the high side of the A/C line to turn it off at highway speed when the pressure on the high side drops below 200 psi.

The system works fine, except that the 95-amp alternator on the van can barely keep up with the electric fan, since that monster is drawing something like 30 amps. Going through the normal channels (Autozone, Kragen etc...), I could find nothing in the 130-amp range for the Aerostar. However, I found out that the Explorer 95-amp version is identical to that on the Aerostar, and there is indeed a 130-amp version for the Explorer. The question is whether or not I can put the 130-amp Explorer version on the Aerostar without screwing things up royally.

Any thoughts on the subject will be appreciated.

 

Sounds like a clever adaptation. Do I understand correctly, the fan is essentially on most of the time, albeit in a variable speed mode except for those time when the A/C is activated and the pressure switch cut-off is working?

As to the alternator, electrically the number of additional amps presents no danger to the electrical system. It is similar to buying a battery with more amperage than the original one - there may be more amps than the starter needs but it still draws only what it requires. Think of amperage as being like water flowing by in a river. There is lots there, but you may only need a glassful or a bucketful at different times. The rest is just there if needed. The downside to a higher amp alternator is having the engine work harder to crank out those amps. With mileage concerns paramount, the minimum alternator required is the one used by the manufacturers.

 

Yes, that's exactly it. Normally, the fan doesn't have to work too hard, if at all. But, on a hot day, in stop and go traffic, it's on almost full blast, especially with the A/C on.

I understand what you are saying about the current, but I'm afraid that the current hot wire coming from the alternator may not be able to handle the added current imposed by the fan. I'm thinking about tapping the alternator directly to drive the fan, via another wire with a fusible link and a fuse. That way, any additional current drawn by the fan won't have to go through the current wiring system and all the vehicle requirements would still be the same.

 

Fellas
I installed the 130 amp alt., with a 1200amp battery. It doesn't matter which one you have. There is no downside to a higher amp alternator. It does not cause the engine work harder to crank out those amps. It spins the same, if the pulley is the same size. The old electric parts guy I know , always installs the 130+ in the loaded vehs. I have air, fog lights, digital dash, a TV, DVD, etc. It will work less due to it will only relay on and off less.
He even has a 150 RV alt. out of the E350s. I would have bought it if it was avaible at the time.

 

Sorry, CndSoldier, but the higher the amperage, the more horsepower (engine load) is required because the magnetic fields are stronger. For gas engines the rule of thumb is 1 hp per 10-15 amps. so figure, 95 amp = 9.5hp while 130 amp = 13 hp. In copper_90680's case it may be a trade off since the engine will no longer have to turn the fan/clutch assembly. Here's a link to alternator upgrade considerations: http://www.zena.net/htdocs/alternators/alt_inf2.shtml

 

AC
I have installed upgraded alts in all my vehs. With no change in milage, drivability,etc. Remember the Alt is not chargeing consently. I phoned the part shop here just to make sure, before I posted. The old fella I get all my parts, said there is no differance. It differs in pulley size. If you have a smaller pulley it spins quicker but takes more power at low RPMs. Vis the reverse. But if you stay the same, for normal driving it has no effect.

 

AC
A great link! Thanks, But I will stick to what I know that works for me. The parts fella worked on my father's cars and truck for yrs. He raced at the old Windsor, Ont drag strip and customs cars at the shop.

 

The alternator will only present more of a load if there is a greater load on it. The voltage regulator will prevent too much voltage from going into the electrical systems. If you install an electric fan, it will draw more power, so that's where the greater load will come from, and will therefore sap some of the power from the engine. An electric fan will be less efficient than a fan directly driven by the engine through a good clutch. The motor has to convert electric power to mechanical power, where there is a conversion loss. The electrical power comes from the alternator converting mechanical power to electrical power, where there is more conversion loss. A good clutch will disengage at a certain temperature or a certain speed, though it is a bit of a load on the water pump bearings. I think that's where the biggest benefit of the electric fan comes from; it does not load the water pump.

You can check alternator loading by running your engine at idle, and start turning on electrical systems like the heater motor, rear defroster, high beams, fog lights, and anything else you might have. The EEC will attempt to keep the engine speed up, but at some point, the engine will slow down from the added load from the alternator.

 

The main reason I went to the electric fan is the crack on the stock fan for the 4.0L. It's disgusting how Ford can let that crap persist. All the 4.0L I have touched have a cracked fan right at the clutch. Overtime, that can vibrate your water pump to oblivion. And those fans are not cheap either. Hopefully, my water pump will last longer this time around.

 

My dad had a 1991 Taurus with a factory 130 Amp alternator (3.0L). This was a Canadian-spec car with and 850 CCA battery and block heater. There does not appear to be much difference between the FWD and RWD engines, so I would assume the bracketry is interchangeable (if required).

Cheers,
Eric

 

> I could find nothing in the 130-amp range for the Aerostar.

How about buying an aftermarket electric fan that only draws 10-15 amps, but, can out blow the Taurus fan. It will cost the same as a high amp alternator.

> The question is whether or not I can put the 130-amp Explorer version on the
> Aerostar without screwing things up royally.

No problem, as long as they match up pulley wise. I have put higher amp Ford alternators from one vehicle to another without any trouble. When I wanted a even higher one in my E-150, I went thorugh the RMP book and put in one from a Mercury and just changed the voltage regulator so the wiring harness matched.

You might want to run a heavier wire to the battery. I put a BX(?)850 battery in my van and it worked well and just barely fit.

 

As far as I can tell, the 130 amp and 95 amp version of the Explorer are identical dimension-wise and with same wiring harness as the 95 amp version of the Aerostar. In fact, the 95-amp version of the Explorer and the Aerostar have the same part number. I haven't checked the dimension of the pulley, though. Thanks for reminding me of that.

 

copper_90680:

Please post any MPG differences with your electric fan. Have considered doint this on my van, in addition to electric fan and fuel pump on my truck. I'm just not convinced that trading mechanical for electric gains horse power, as already noted the "mechanical" alternator drains the HP's instead of the clutch (or fuel pump). I know this isn't why you went to an electric fan, but if an added benefit is mileage (and less noise), I'm right behind you, even though I've already replaced that stupid plastic fan.

John

 

are there any cars/trucks/vans that have an electric fan i can just get at the scrappers and put in?

 

Just go to a rebuild shop and tell them you want a 130amp rectifier. This will make your alt a 130 amps. I use to rebuild Alt and starters and when you put a large CCA battery in you need a bigger amp Alt to keep it charged.

I did this to all my cars and trucks and never had a problem in cold weather starting. Also make a ground stap from the Alt to the engine block out a number 8 strained wire. This will insure 100% output and makes the alt last longer.