Need opinions on Dual fan Set-up

[Bugetexpedition]

I have a 1977 ford f250 with a 400 CI engine that carries a large truck back camper. Last year I had some issues with overheating. I removed the belt driven fan and just received two 12 inch electric fans from an internet store.

Here are the questions:

1. Should I run one fan full time and then have the second fan on a switch in the cab to manually run when the truck is under a heavy load.

2. Should I have both fans on switches to be turned on manually

3. should I have one on a thermo switch to turn on at a certain temp, and have the second one on a switch in the cab to manually run when the truck is under a heavy load?

Scott

 

[mog]

Are your fans side by side, or is one behind (pulling air) and one in front (pushing air) ?

If they are side by side to cover the whole radiator air, run them both at the same time regardless.

I use an electric fan (single) on my FJ40 and have found that when it is on, even with the vehicle stopped, it keeps the temp cooler then driving at 60 mph without the fan running. I have it set-up with a three way switch with the center position being 'normal' so the fan is control by a thermo switch, up is a manual override to always on, and down is a manual override to off (for water crossings). I would say to use a thermo switch and have a manual override to on, so you can turn on prior to long hills etc. And FYI, my first two thermo switches were high-tech electronic switches that both failed. I switched to an old style thermo bulb that going in the radiator hose and has a capillary tube coming out to the controller that has a simple pot to adjust the 'on' temp. It has worked great for the last 15 years.

 

[chasespeed]

I would, make a "shroud" to cover ANY area not covered by the fans.

THEN, I would wire both seperately., with a relay on a single swtich to kill power to both, for water crossing, etc.

I would have both on a thermal switch, have them set the same, or have one set a little lower, than the other. If you have A/C, add in another relay, to kick on BOTH with the a/c.

Fan 1, 30amp fuse, kill relay, themal relay, set at... say 180*

Fan 2 30 amp fuse, kill relay, thermal relay, set at ... 200*....

THIS way, if you have a problem, with any single part of the circuit, it can be fixed easily, but, you will also have another fan running regardless.

Redundancy is your friend in some instances....

Chase

 

[dlbrunner]

I would make sure the entire cooling system is up to snuff before adding gizmos on. Make sure the radiator is clean and free of deposits. Upsize to the largest possible size when possible.

Make sure the water pump is either new or working well.

check the thermostat....upgrade to a "Fail open" type.

Replace the fan clutch.

After you know all that stuff is good, then I would attach an electric fan on the outside of the radiator as a "Pusher". If it were me I would not fool around with automatic switches at temp etc. a simple On/off switch is all you need.

Also if you don't have one install a decent temp guage so you can know when to turn the electric fan on.

Keep it simple FWIW