claytonisbob

iTrader: (1)

if you have a multimeter, that would be a good way to test it. I have a feeling you burned that thermo-switch up when you ran it with the first wiring diagram you posted. They're probably not made to run 40+ amps though. When you get everything wired up correctly, you should be able to hot ground the wire that would be going to the thermo switch to kick the fan on. If that works, and it never kicks on when it gets hot, your switch is toast. Or again, boiling pot of water and a multimeter would be an easy test too.

BTW, the mark viii fan is pretty awesome value, and definitely needs a 60-75 amp relay. They don't necessarily need that many amps when running, but the kick-on amperage spike is pretty high. I ran a 75 amp relay and a Dakota Digital PAC-2700 for a while with my MarkVIII fan and it worked flawlessly. Now that I'm going with an LS (with a computer) it made my wiring for that a bit easier.

demonpixel

iTrader: (19)

Pooter, I wired it EXACTLY how you and the diagram said to do. Fan refuses to turn on.

When the new switch gets here, I bet it'll work then.

01cherryreds10

iTrader: (9)

Do you have a 1 speed or the 2 speed? I've got the 2 speed on my 79' SBC Malibu and I used a Bosch 75A HD relay with a Derale thermostatic switch wired in. It's not like a normal relay, is one with screw hold downs.

00pooterSS

iTrader: (40)

Did you hit the green wire with a positive signal and see if it ran the fan? That does the same thing as when the thermoswitch gets hot and signals the relay since they are connected to the same pin.

Your first wiring diagram shows you ran the other side of the thermoswitch to the fan itself, that could have damaged the thermoswitch.

But if you have wired everything correctly, and the relay is good, then when you touch the green wire to a positive wire the fan will run.


Test your pins on the relay connector with the relay out. Make sure you have + power at the pin that connects to relay terminal 30, make sure you have ground at terminal 86, connect the green wire to a positive and make sure you have + power at 85. Jump 30 to 87 and make sure the fan runs. If you have all these above and the fan does not run when you jump the green wire to hot you have a bad relay, if it does work but still does not work by temperature you have a bad thermoswitch.

00pooterSS

iTrader: (40)

Good info, I think he may have toasted the thermoswitch too. Did you have problems running less than a 30 amp setup? That fan must pull a lot of amperage, I know nothing about it, how big is it? Out of curiousity did you ever do an amp draw to see how much that thing pulls?

claytonisbob

iTrader: (1)

I never measured the draw it pulls, but I read somewhere it can spike to above 70 amps when the fan kicks on. The cool thing for me is my setup cools my engine so quickly (the fans are never on for very long, almost never come on when I'm driving), I don't think the amperage being used is that big of an issue (I believe it's around 40 or so amps continuous), especially for CS alternators or newer.

I know this is unrelated but I want to say that DD PAC-2700 is a pretty sweet fan controller. It will handle 2 fans if you have them, and if you're using an autometer temp gauge (it supports several types), you can program it to use that signal.

demonpixel

iTrader: (19)

Ok. I don't think I toasted the thermoswitch, because like I said before, I wired everything up through the relay the first time, and it didn't work.

Then I wired a cheapo switch through the relay instead of the thermoswitch, switched it to the on position, and the fan turned on.

I think the thermoswitch was toasted when I got it. Summit says a new one should be here in two or three days, so we will see.

I did not hook up power to the green wire. I can try that tonight. I'm sure it will turn the fan on.

00pooterSS

iTrader: (40)

Oh okay, your diagram shows that you did hook the thermoswitch to the fan is why we are saying that doing that may have fried it. If you didn't hook it up the way your diagram shows and wired it properly from the start then there is something wrong

demonpixel

iTrader: (19)

Ok I can see how you would think that because that's the diagram I posted first. Sorry, I shoulda specified. I hooked it up the way in the diagram AFTER I went through the wiring instructions, which was through the relay, etc. The only wire I didn't connect was the blue wire for a second fan, and the green wire for A/C.

After it didn't work, I removed the thermoswitch from the circuit and replaced it with a regular cheapo switch. THAT worked. The fan turned on. Then I removed the relay, and wired the thermoswitch like I did in the diagram. I know it's not meant for a huge draw, but I thought I would at least see the fan turn on. I did with the other switch.

I know that getting defective parts happens, and it's probably more common than we'd like to think, but I just wanted to check on here since i've never set up a fan switch like this before.

I called Derale's tech line today. Apparently there is only one guy and he is off today. Awesome.

00pooterSS

iTrader: (40)

Oooooooooooohhhhhhh Ok. Yeah if you put a switch in place of only the thermoswitch and ran a hot to that switch and it worked then you had it all done right and the thermoswitch was bad...

00pooterSS

iTrader: (40)

That is alot of amp draw, gonna need a billy bad *** relay and relay connector for that bad boy. And that controller sounds awesome, especially if you can set it off gauge temp.

demonpixel

iTrader: (19)

Will that PAC-2700 work with an analog temp gauge?

demonpixel

iTrader: (19)

Good question. How do I verify if this is a 1 speed or a 2 speed? Just use the third wire?

00pooterSS

iTrader: (40)

Its a one speed, it has a single wire output to the fan motor, the relay turns off and on only. So its full power on or full off.

00pooterSS

iTrader: (40)

third wire? you mean the other hot output wire?

01cherryreds10

iTrader: (9)

If it's a 1 speed fan it will still have the 3 wires. Only one of them will just be a dummy wire and lead to nothing inside the fan. To check which one you have, there is an inspection cover on the 1 speed, and on the 2 speed, there isn't. There's a good picture on google images of the comparison between the two. It may just of been a silly mistake and you wired up the wrong wire to the thermstatic switch. Either that or you have a bad switch. When I put my fan in with the Derale controller with the threaded probe, I cooked the relay and switch from running it for just 15-30 seconds. Those fans need the HD relays.

demonpixel

iTrader: (19)

I got the new switch from Summit today. It's the same part number, but the base of the switch is much shallower. Well, I tested that and it didn't work for a while with the probe in boiling water. So I thought what if I submerge the whole thing? BINGO.

THE PROBE DOESN'T DO ****. THE BASE OF THE PROBE IS WHAT GETS THE TEMPERATURE READING. I made a pic to make this a little more clear for any newbs that come across this:



I thought if you heated the probe, the heat would travel to whatever read the temperature. Nope. I think the probe is just there so you can stick it through the radiator.

So I tested the old probe switch, the one I thought was originally f'd, and that one worked too.

I know all this sounds stupid, but like I said, I've never tested one of these things before and I didn't know

Thank you for all your help; I can continue on with getting this thing started!

00pooterSS

iTrader: (40)

Thats odd... it should have worked off of just heating the probe since that is all that is put into the radiator. Hopefully once installed it works properly. Glad you figured it out, now get that friggin thing running already, its been forever geez!