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Don't press your luck!
 Sure, you know how to work on old trucks. Or maybe you're just starting in the hobby. Either way, safety is best learned through OPM (Other Peoples' Mistakes), not OJT!
Either as newly discovered wisdom, or a refresher, please read this article and live safely with your old truck!
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Forums60
Topics128,763
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Most Online1,229
Jan 21st, 2020
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Joined: Jun 2010
Posts: 545
OP
'Bolter
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i have a 1954 chevy p.u.
with 235 3 speed
i would like to add a extra
fan in front of radiator
should it push air or should
it pull air through radiator
just would like extra cooling
thanks keith
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Joined: Jul 2010
Posts: 619
Shop Shark
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Keith, I have a '57 with a 235. When I added A/C, I installed the condenser in front of the radiator and installed two 9" electric pusher fans in front of the condenser. The fans work off a relay that powers them when the compressor turns on.
I did it more to increase air flow over the condenser coils at idle than to cool the engine. But to your point, you'd wire the fan to push air.
You have to be careful when combining an electric fan with a fan run off the engine. Sometimes the combination can create a vortex that actually reduces effective air flow through the radiator because they work against each other. I got lucky when I did mine, but I knew that there was some risk. I figured I'd experiment with trial and error...and I got lucky.
If you need more air flow, you might want to consider a six blade fan as an option instead of the pusher fan. The six blade fans were a dealer option to increase air flow.
Matt
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Joined: Jan 2000
Posts: 2,231
'Bolter
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I picked up a pusher Hayden brand fan from local auto parts, mounted out front a great item to have in traffic hot days etc.
Switched on/off via a toggle switch.
Best of luck
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Joined: Dec 2008
Posts: 1,900
'Bolter
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i would like to add a extra
fan
What's wrong with it?
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Joined: Aug 2011
Posts: 149
'Bolter
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What would be good to do is......
I have AC on my 51 GMC stock 228. I use the stock fan, 6 blade and there is a compressor controlled elect fan in front of the condenser to push air.
I have thought of wiring in line the power line from the compressor to the fan with a hot toggle switch to turn on the fan even when the compressor isn't on. (Like in stop and go doing traffic) This would require a diode to keep the power from feeding back to the compressor when the toggle switch is on.
Don't know what diode would be best or am I barking up the wrong tree to get this accomplished? Experts? Your opinion for both of us?
Thanks, Mike
Last edited by pdlightning; Fri Apr 14 2017 08:41 PM.
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Joined: Jul 2010
Posts: 619
Shop Shark
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I'd use a DPDT switch instead of a diode. It has two separate circuits controlled by one toggle. It will have six lugs on the back. Run the power for your direct-wired fan to one of the middle lugs. Run the compressor power feed wire to the other middle lug. Run the outlet wire to the electric fan to one of the end lugs on the same side as the fan power wire. Run the outlet wire to your compressor to the end lug on the opposite end of the switch from the fan outlet wire and on the same side as the compressor wire. You will have two unused end lugs, one at each end and on opposite sides.
Wiring it this way will isolate the compressor to prevent feedback. When the switch is toggled one way, the A/C unit will run as normal. That's your default position. When it is toggled the other way, the power to the A/C unit is disconnected and the fan will operate on its own.
Matt
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Joined: Feb 2004
Posts: 25,940
Kettle Custodian (pot stirrer)
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Electric cooling fans and manual toggle switches are a recipie for disaster unless there's also an automatic shutoff in the circuit designed to stop the fan when the ignition switch is turned off. Otherwise it's only going to be a matter of time until you forget to switch the thing off and run the battery down. A simple automatic on/off circuit that incorporates a thermal switch set to a predetermined coolant temperature is a lot wiser choice.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!"
Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Ernest Hemingway
Love your enemies and drive 'em nuts!
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Joined: Dec 2008
Posts: 1,900
'Bolter
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A fan is completely unnecessary above 40 mph. If you have a temperature problem at cruising speed a fan won't fix it.
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Joined: Sep 2014
Posts: 388
Shop Shark
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I installed one in front of the rad for the heavy traffic city driving days. Does a great job. Toggle switch is fine, its hard to walk away and leave it on because its easy to hear running.
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Joined: Aug 2011
Posts: 149
'Bolter
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Wow , you guys are the best! Thanks for the input!
If you do the DPDT switch part and wire in an indicator light when powering the fan OTHER than the compressor, wouldn't that work? I understand the part about leaving it on and walking away and killing your battery, but the bright indicator light would or should solve that. The manual pusher fan would only be used at slow speeds to help in cooling during parades and stop and go traffic on hot days.
Thanks again!
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