Electric fan wiring questions...

[blazerbones]

I have a '90 350 TBI that I'm putting electric fans on. Stock Motor. Where are the best places (on intake or heads) to put the sending unit for the fans? The sending unit is 3/8 - 18 NPT.

 

[dyeager535]

Intake is likely the best (should give the hottest reading), but in the heads will work if that's the easier way to do it.

 

[Mike D]

What is the on - off temperature of the sending unit? If it is 180 - 190 the intake is best if it is 210 - 250 the engine head by the exhaust. Is the sending unit adjustable? Don't forget to use 1 or 2 relays to turn on the fans. Most fans draw 20 amps each. Above all do not suspend the fans by supporting them thru the fins. The (side) torque generated when they turn on will cause the radiator to leaks at the attaching point(s).

 

[blazerbones]

Great info. I have the mounting all figured out... should be sturdy and robust without hurting anything. I think the switch turns on at 190ish. I'll have to check.

Trying to figure out exactly how I want to wire it... the big fan has 2 speeds, so if I want complete manual control as well as automatic temperature control... the wiring may get just a bit complicated for my tastes.

I'm not exactly sure where the fittings can fit into the head or intake... but based on your replies... figuring that out should be the easy part me thinks.

 

[dyeager535]

I'd probably plan on running the single speed as the primary, and run the secondary as high only, tied into the AC if necessary.

If you can, don't hardwire the fans/relays, so that you can swap the wiring for them easy. That way you can figure out if you need the high speed fan, and reverting to that setup would be easier.

Running the high speed fan when not necessary is just wasting gas and taxing the electrical system unnecessarily.

I've got a dual fan, the primary is plenty to keep the motor cool, the secondary never turns on. Since I wired them up using the same connectors, I can simply swap the relay plugs so that both fans get used instead of one just sitting there for years with no use.

 

[Mike D]

Concerning the AC. Use a relay ( controlled by the AC clutch ) that will turn on a fan when the AC compressor turns on. Most newer vehicles have marginal cooling systems and older vehicles have age related cooling fin restrictions that would appreciate the extra help a cycling fan would give.

Concerning the temp switch. Auto Zone , Advanced,And NAPA carry adapter bushings to ideally place the switch where you want. They are located behind ( and below ) the main counter.

 

[blazerbones]

Okay, thanks guys.

I'm going to have the 185degree switch fire the low speed on big fan relay... the 200degree switch fire the small fan relay... and the a/c turn big fan on high/simult with small fan. I'll have an on/auto switch as well.

Anybody know the p/n for the factory ford weatherpack connectors on the 95-98 windstar fans... one 2 prong and one 3 prong connector?

The 2 Ford dealers by my house have no idea... or I could just splice in new plugs I guess...