Simple 2 speed fan wiring

[misterfubar]

I know this subject has been beat to death and I searched and asked around and couldn't find a simple 2 speed fan wiring diagram that suited my needs. So I decided to draw one up.

I want a single 3 position toggle switch, and I don't think using more than 2 relays is really necessary.

For my Scout, the low speed is more than enough for daily driving and I'd like to use it with a temp switch in the block, I want to be able to manually put the fan in high for when I need it, and I also want to completely disable it for water crossings. I also want an indication of what speed the fan is in and a warning light for when I have it off. I haven't decided if I want to wire it straight to the battery or just have it hot with the ignition on, where I wire the toggle switch will determine that.

I know people have said they've used 30 amp relays without any problem, but I feel that just isn't enough for the amperage that the fan uses on high.

Let me know if there are any problems with this and I will make the changes.

[Rock Tractor]

I pulled my Taurus fan out and went back to a mechanical fan. I had it on a 3 way toggle and 2 relays. 30amp relays are plenty, I ran it that way for 3 years.

[scout254]

looks correct.

Like you said, the low side will come on when thermal controlled kicks in. A adjustable thermal control switch would be better, then you can have it turn on towards the temp you want it at.

Low fan would definitly shut off when high is switched on.

I would definitly tie the 3 toggle switch through the ignition switch, so the "OFF INDICATOR" wont be "lighted" when parked with the keys in yo pocket:flipoff2:

Do three colors if needed for the bulbs, like red(off), blue(low), green(high)

30 AMP is just fine, I use them everywhere.... lights , fans, headlights......

[misterfubar]

I may end up going with an adjustable switch, but I've had problems with them in the past. I guess I could pony up the money on a good one. I'm thinking I should be able to find a thread in with the temp range I want, just have to dig out the catalogs.

Or I could probably just leave well enough alone, the little electric fan I have on there now rarely turns on and it's set at about 195. I already have the taurus fan and probably all the relays and wiring I need though, so who knows.

I know a lot of people have never had any problems using 30 amp relays for the high side, but I've read that the fan pulls as much as 100 when it first turns on and is spooling up. When it comes to electrical I tend to err on the side of overkill :smokin:

[Snoopy]

I'm not electrical wiz so what happens if you power both the Low and High at the same time? For example, if your switch was an 0ff-1-1&2 type of switch?

[Dhmoto111]

the bad thing about that diagram is that the switch doesnt have circut protection

[misterfubar]

I'm not electrical wiz so what happens if you power both the Low and High at the same time? For example, if your switch was an 0ff-1-1&2 type of switch?

With that type of switch it would trigger both relays, but the fan would run in high because the low relay gets it power to the common through the high relays normally closed contact.

[Dhmoto111]

I'm not electrical wiz so what happens if you power both the Low and High at the same time? For example, if your switch was an 0ff-1-1&2 type of switch?
that would be the same as hi

[misterfubar]

the bad thing about that diagram is that the switch doesnt have circut protection


Good point, I should probably add it on there. I know that I would fuse it, and I hope that anyone else would do the same even if it isn't on the diagram.

[Urban Wheeler]

that would be the same as hi
No that has been discussed before. Look in the FAQ, there are fan wiring threads. If you power them both they will fight each other and will will get more current draw and less airflow.

[misterfubar]

Yeah it has been discussed in the Faq, but if you look at THIS diagram there is no way for both speeds to be powered at the same time.

[Urban Wheeler]

I see, and that is a nice idea to set it up that way. Even if the switch malfunctions there is no way to run both speeds at the same time.

My post was more or less to the other guy who said that running both would be the same as hi speed.

[paultyler]

I pulled my Taurus fan out and went back to a mechanical fan. I had it on a 3 way toggle and 2 relays. 30amp relays are plenty, I ran it that way for 3 years.

Why did you switch back?