Electric fans, revisited

[MaineShark]

Alright, I'm ditching the mechanical fan. One of the previous owners put in an incorrectly-sized flex fan, and the car just ain't cooling.

So, I'm going to get one of those dual-11" SPAL fan setups. I've found them for around $250, which seems pretty decent, considering the price of a new mechanical fan, clutch, and replacing all the shroud gaskets to make it work.

Here's the first question: how have people wired these in? My current thought is to have one always-on, and the other on a thermostat.

Second question: I've seen this setup listed as "25 amps"... is that total draw or per fan?

Third question: I've seen an adapter that fits in the lower radiator hose, which has a threaded bung for the thermostat switch for the fans. Obviously, this created the potential for two or three more leaks, but I can't think of any other place to mount the switch. Thoughts?

Fourth question: mechanically, what is the best way to mount the fan setup to the radiator?

And I think that covers it, for now.

Joe

 

[69MyWay]

Joe,

The full Spal kit from Dewitt has an upgrade feature for the relay kit. It is simply a pair of relays and a thermo switch of your choice, I think 160 and 180 are available.

You screw the switch into a head or the intake. It makes "ground" when the switch hits temp. That ground signal goes to the relays where you have the 25 amp battery direct power, and a small ignition on power wired to the relay. The ground from the temp sender closes the circuit with the ignition key on loop, then that pulls the large direct battery (or off your starter terminal) 25 amp power into play and runs it out to the fan motor. On the other side of the fan motor, you run it to ground.

They are each 25 amp, but don't pull that much draw. I would however suggest you plan on having at least a 100 amp alternater in that car by the time you are done.

The Dewitt fans come with brackets to hook to the radiator, or you can get creative and do as you please.

Mine come on at 180, and for the most part stay on after that as it is rare for me to drop under that temp. I also wired a third relay in to close a second ground circuit when the a/c compressor is engaged. You will need to look into this so that your a/c will cool right from the start, and not over heat the condenser.

 

[MaineShark]

Thanks.

Another idea/question: from the factory, this car has an auxilliary electric fan that turns on whenever the A/C is on, and if the temp gets above some point (I think I heard 230). Anyone know where the thermostat is that triggers this fan? If I could replace it with one with a better temp setting, I could re-work the existing wiring to trigger the relay for my larger fan(s), and have the A/C-on, fan-on thing already wired for me.

I was looking at the DeWitts fan setup, but it's a bit pricey. The dual-11" SPAL fans are only $250 from other sources, and DeWitts wants $125 for the brackets and wiring (comparing their kit price to their fan-only price), so even if they were willing to sell me only that stuff, without the purchase of a fan from them, I think it's a little steep. Just my thoughts on the matter...

Joe

 

[sscam69]

Joe

Chris explained the wiring pretty well.

I wired the fans through the fuse box and have mechanical switchs to turn the fans on and off at will. I can actually run with just one and it will hold at 190. If you do go with a switch make sure that the switches can handle 25A each. I used one for each fan that could handle 12 A thinking that the total draw was 25A for both and melted one of them.

Again as Chris stated make sure you have an alternator that can handle the load. I had a stock replacement and the battery was slowly being drained. Until I got the East Coast Auto electric 110A alternator. Headlights were brighter to. Your going to have to convert the Alt. to a one wire which is easy. Look for a post on this subject by me.

Finally Painless wiring has a temperature control switch that screws into the intake or the heads. Theirs was the only one I found at the time that actually didn't require you poking the sensor through the radiator. Needless to say I wasn't to thrilled when I actually had to do it with my new $500 aluminum radiator! I was thrilled when I found it. You can get it through summit or jegs. I have one but the wiring on the car is kinda worn and bubba got ahold of it and its hard to get consistant voltages across the car. I just removed it and put it aside for now.

I mounted the fans on the radiator by using the plastic straps that go through the radiator. I used a total of six, 3 on top and 3 on the bottom. People don't speak to highly of them but I haven't had any problems with them. I also purchased some weather stripping as there is a 1/4" gap between the top and bottom portions of the fan shroud. Just tucked it in there and ran that plastic straps through them to hold the stripping in place. It basically seals the shroud against the fan.

Hope this helps

Frank

 

[sscam69]

oh and the hook up for the aux. fan is on the passenger side. the connections are perpendicular to each other and I think it has a pink and blue wire. Mine runs right along the A/C lines.


Frank

 

[MaineShark]

Which plastic straps did you use?

Regarding melted switches: that's why you use a relay The relay takes the full amperage - the switch only needs to take the amps necessary to close the relay.

I think I may go that route, though: one fan wired always-on, and the other on a mechanical switch. Any good places to mount a switch, where you can get at it, but it doesn't stick out like a sore thumb?

I ordered the fans today. $262.45, shipped. Hopefully, I can get them installed soon, because this is getting a bit ridiculous. It was 80 today, and the temp hit about 240 on the highway. Not good, especially since it's so much fun to drive in the warm weather with the tops off.

Are there any good alternators that will just plug in? I'm trying to keep my wiring modifications to a minimum, since ol' Bubba definitely had his way with this car (I'm guessing when the engine was changed). I found a wire running all the way from the firewall to the nose, not connected at either end. "easy conversions" might not turn out to be...

Joe

 

[MaineShark]

Thought I'd bring this back up. I have the wiring pretty much figured out, but I can't decide where to mount the switch. Any thoughts?

Joe

 

[Gunther]

Hi
I mounted a pull type switch near the wiper door override switch.
( early chrome bumper C3 ) to activate the secondary fan manually. It is also coming on automatically when water temp gets to 230 F.
The primary fan is auto controlled by a temp switch mounted in the intake near the water thermostat housing, switching temps are 195 on, 185 off. Thermostat is 180 F.
One fan is enough to keep my 68 big block cooled in stop n go driving.
As soon as the car is moving, no more fans required. The alu rad takes care of the rest.:cool
Good luck Gunther

 

[69MyWay]

I sure wish you were not planning on running a switch. I realize it is a more simple direct way to do what you want done, but it takes away from having an OEM style final product.

I have a buddy that refused to run a temp sensor and relay on his V8 Jimmy. He has some super nice switches on the lower knee dash panel. He was the only one that drove the truck so it did not matter.

The truck was stolen right out of his driveway one night. The perps that took it did not know about the switches. They ran the truck up by the airport, and cooked the engine. They dumped it in a ladies front yard where it proceeded to puke anitifreeze on her grass.

Long story short, he got the truck back the next day, it was not a total loss per the insurance company, as the primary damage was the blown head gaskets, etc. It made him sick.

I think about that now when I think of simple hard wired toggle switch fan units. I think they should be wired so that they are either always on when the key comes on through a relay, or just through a temp sensative relay.

Just my .02.

 

[MaineShark]

Well, what I was thinking, was one fan wired to run whenever the car is running, and the other wired to a switch.

The second option might be to have that second fan wired to a thermostat instead of a switch.

The third option is to have each on a thermostat, with two separate temp ranges.

The fourth option is to have both come on with one thermostat.

Personally, I prefer the third option, but I'm not sure I want to find mounting places for two thermostats. But I'm not even sure where to mount one. I can't seem to find any removable plugs, or such. Is there any way to mount a thermo switch without drilling into something?

Joe

 

[69MyWay]

Joe,

Pep Boys (the only ones I have found with this) sells a cooling fan relay kit that comes with these really cool thermo switches that push into the radiator. I have used them on several different car projects to trigger the fans.

They come on at 180 and shut off at 170 with relay and wires for about $30. They also have one that has a fully adjustable switch, and I think it is about $40.

They work great, and I have not had one fail yet, and have had them on: My V8 S10, V8 Fiero, 85 383 Vette, 90 Vette, 36 Ford w/ LT1, 1990 1500 truck with LT1 conversion, 1989 1500 chevy truck with LT1 conversion, 86 V6 Fiero, 88 Cavalier....and the list goes on.

The funny thing is, I can't remember the name brand, but I swear it start with an "R".

Other than that, you can get the 180 temp switch from Mid America for the C4. You can screw it in a head or intake. You only need one sender, and can trigger as many relays and fans as you want from there.

 

[Bob Chadwick]

Another idea/question: from the factory, this car has an auxilliary electric fan that turns on whenever the A/C is on,

Joe,

What are you going to do with your aux fan. My car doesn't have a cooling probelm per se. It has a problem keeping the a/c cool at idle in traffic. If it it will fit on my 77, I might be willing to take it off your hands.

Bob

 

[MaineShark]

Chris: thanks, I'll take a look at those.

What are you going to do with your aux fan. My car doesn't have a cooling probelm per se. It has a problem keeping the a/c cool at idle in traffic. If it it will fit on my 77, I might be willing to take it off your hands.

I don't know if it will fit your '77, but I'm not going to need it, so we can figure something out once I get it removed.

Joe

 

[MaineShark]

Alright, new plan: I'm going to wire in a temp switch. I'm also going to wire a three-position switch to each fan. That will give me the control that I want - I'll be able to select each fan to on, off, or automatic. Should make it easier to diagnose problems, and I just plain like having control over things in my car.

Bob: are you going to be wanting just the fan, or the shroud as well? The fan mounts to the shroud, but you might be looking to do a custom installation.

Joe

 

[bossvette]

you may want to try a flexalite black max it comes with a thermostat built right in have been using one for 3 years with no trouble

 

[Bob Chadwick]

Bob: are you going to be wanting just the fan, or the shroud as well? The fan mounts to the shroud, but you might be looking to do a custom installation.Joe

Joe,

Can you take me a picture so I can see how the thing sits and then I'll let you know.

Bob

 

[MaineShark]

Joe,

Can you take me a picture so I can see how the thing sits and then I'll let you know.

Bob

I took the fan out of the shroud, in hopes that the shroud would become flexible enough that I could remove it without removing the radiator, but no such luck. Once I take the radiator out, I'll pull the shroud and re-install the fan so I can take a picture.

Joe

 

[Bob Chadwick]

Thanks Joe.

 

[MaineShark]

Amendment to new plan... if I wire up a delay circuit (say, a minute or two) for the always-on side, I gain a number of things:

Better warm-up.
Safer electrical system (I won't have a whole bunch of large loads coming on at the same time).
Dead battery protection (if the car is hard to start for some reason, I won't have the added drain of the fan, killing the battery all that much quicker).

And, I can wire in a shorter delay (say, a seatbelt buzzer timer), and a pigtail to the thermo switch, I can have it automatically change to the short delay when the car is already hot.

Joe

 

[MaineShark]

Alright, I sat down with my wiring diagram, looking for the seatbelt buzzer delay module, but that seems to be a single unit - delay module and buzzer.

But something else jumped out at me, while I was looking through it: the electric rear-window defroster control module. This normally powers the defroster coil for a few minutes after you push the momentary switch, then shuts off. If I connect it to a normally-closed relay, it can break a circuit for those few minutes. So, I just wire it to the ground side of the relay coils for the fan relay, and it will not be able to energize until the timer shuts down and allows that other relay to close again. I'll splice into the starter harness, somewhere between the ignition switch and the starter, so the delay will be triggered as soon as I turn the key to "start."

If I also install a second thermo-switch (say, a 210-on, 190-off one), and splice it into the ground wire, between the fan relay and the normally-closed relay, then it will act as a bypass, if the temp gets too hot.

Thoughts?

Joe