The Stovebolt Site Forums The Shop Area Engine Shop fan question

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

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

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

i would like to add a extra
fan

What's wrong with it?

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

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

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

A fan is completely unnecessary above 40 mph. If you have a temperature problem at cruising speed a fan won't fix it.

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.

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!

Search Ebay for "electric fan switch". There are several kits for less than 20 bucks, with free shipping. It includes a coolant sensing switch that turns on at 185 degrees and back off at 175, a circuit breaker, a relay, and wiring, connectors, pipe fittings, etc.

It's an almost idiot-proof way to turn a cooling fan on and off, unless you're a particularly persistent idiot! If you wire the relay to a constant-hot circuit, it will even fix the flooding problems associated with hot soak after the engine is shut down on a summer day.
Jerry