The Stovebolt Site Forums The Shop Area The Electrical Bay Electric fan and relay switch

Have an electric fan and relay question
I’ve had some engine cooling issues I’ve been working on
So I just installed an aluminum radiator with electric fan took the metal fan off today I hooked up the wires for the relay per instructions fan kicked on when truck got warmed up
I wanted to change the air flow direction and took wires apart I touched the fan wires together in the process and blew the fuse on the relay replaced the fuse and fan wouldn’t turn back on if I put the hot wire directly from the battery to fan wire and ground it works if I hook up the fan to ignition wire and ground it works as well
So I’m thinking of just wiring the fan to ignition only hot when key is on and just run at all times
Any thoughts? Almost forgot it’s a 52 truck with a 235
Thanks

You likely burnt up the relay as well as the fuse. I'll bet a replacement relay will fix it up. It's probably best to have the fan thermostatically controlled with the relay, not running continuously with ignition on. Is there also a thermostat in the relay circuit? That might be suspect as well.

Just finished looking up a new relay kit I’m going to get another one so is it also possible I burn up the temperature switch on the thermostat housing??
Thanks

You can check the temp switch with a multimeter. Connect the meter on each wire to the switch (after disconnecting them from anything else) and you should see the switch as open circuit until you heat it up (a heat gun should work), and then it should show closed circuit. I would check that before ordering a relay kit, as the temp switch is probably cheaper and if it's bad the relay still won't work. You can also check the relay by shorting the two wires connected to the temp switch, and the fan should run.

Is there a good reason for all the monkey motion involved in using an electric fan? There's a perfectly capable fan drive there already- - - - -called the engine- - - - -and it tends to be idiot-proof.
Jerry

Jerry,

I've never understood why so many people feel the need to 'Improve" the cooling system of antique cars. With a few exceptions, such as flathead Ford V8s, the original engineers knew what they were doing and the radiators, water pumps, and fans are perfectly capable of keeping the engine temperature where it needs to be.

All I ever drive are antique cars and not a single one of them has had any modifications to their cooling systems (except an overflow recovery tank on a couple). All of them have mechanical, engine driven fans - most of them fixed blades - and I've never overheated or suffered from vapor lock.

I put 200+ miles on Ol' Roy this week and spent 1 1/2 hours in bumper to bumper Atlanta traffic on Wednesday afternoon. Average speed was less than 20 mph. The engine never sputtered or coughed and the gauge crept up to about 200 from its normal 180.

Once I got moving at 55mph, the gauge settled back down to its usual 180.

I've actually seen people install electric fans that actually made the engine run hotter because it blocked airflow through the radiator.

If the engine is getting too hot, the problem is probably not going to be fixed by an electric fan.

Some folks are always in search of the "Easy Button"- - - - -instead of spending half the time, energy, and money- - - -solving the underlying problem!
Jerry

The main issue with electric fans is they have WAY less horsepower available than the engine driven fan. So to expect them to provide as much cooling as an engine driven fan is pure folly.

That being said, the OP said nothing about his engine getting too hot. And maybe his electric fan is providing adequate cooling. Possibly so if he doesn't load the engine that much.

He asked for assistance to troubleshoot the fan not working, not for someone to tell him to ditch it and go back to the engine driven fan. It's his truck and if it works for him, then no one else should have a say in what to do.

In one of mine with electric fans I run a relay as well the thermostat provides ground to the relay to turn on and off. I spliced into the thermostat wire and have wire running to switch that’s in cab. It grounded to dash. It can be flipped to provide ground to relay and turn fans on even when thermostat is not on.

Just check on your parts. I’ll bet that relay blew as well

WOW JERRY

I went through the entire process with the cooling system unclogged the block drain flushed out engine after removing one leaking freeze plug and also replaced the non leaking freeze plug as well, the fan blade just doesn’t seem to turn fast enough to keep engine cool enough,
The stock radiator has Been gone through a few years back.
New thermostat and hoses I do live in a hot part of California so I was hoping a new aluminum radiator and electric fan would help was working great until I accidentally touched one of the fan wires and blew the fuse and possibly the relay.
A new relay will be replaced soon
I do dread having to post questions and always expect back lash to my post whatever it may concern but part of the process here on this website
Thanks to all who comments back
Thanks

Just FYI...
Flipping the power leads will reverse the spin, but not nessesarily the efficiency. Several fans are designed to be pushers OR pullers and horribly run in the opposite direction.
Some blades can be flipped and retain the efficiency, but it all depends which one you have.
Try everything and anything to fix. I'd try all to get ready for summer driving.

latroca52 Sent a pm

Got the pm thanks HBC
Getting it figured out

And for the fans that do have the horsepower and CFM, they cost a pretty penny.

A big one that most folk forget that greatly improves efficiency, is a fan shroud. Whether you are using a mechanical fan or an electric fan.

Second that on the fan shroud. One thing I did notice when I went to electric fans-or rather, my wife noticed it-was that the whole rig was so much quieter on the highway. That big ole' flex fan eats 20hp while shrieking and shaking like a banshee at speed. The whir of electrics is almost inaudible on the road, and the engine still stays cool if the setup is properly sized to the vehicle's cooling needs.

Low compression and low speeds back then meant that the four blade water pump mounted fan was adequate, mostly. Nowadays with (sometimes) more compression and always much faster traffic means that it's OK to look at modern solutions to modern problems of keeping it cool.

I did also notice a slight MPG improvement upon removing the flex fan. Not a big one, but hey 5-10 more miles on a tank of gas ain't nothin' in this age of expensive dino juice.