Temperature switch ideas?

[1987cp]

Working on ways to switch a 2-speed Taurus fan. So far I've looked through a bunch of OE switches on NapaOnline.com and found only a small handful that look suitable. Going this way, I'd have to use two switches to switch both speeds automatically, unless I can find a dedicated two-speed switch that I like, and most or all of those appear to be metric threaded (have to buy or make a fancy adapter bushing).

Here's what I've found so far in the way of OE switches:

FS120SB, $13
Temp Rating : On 193-207 deg F, Off 175 deg F; Thread Size 1/2"

FS103SB, $22
Temp Rating 200-210 deg F; Thread Size 1/2"

FS125, $27
Temp Rating : On At 205 Deg F; Thread Size : 1/2"

FS300, $27
Temp Rating : Normally Open, Closes At 185 Deg F; Thread Size : 3/8"



I found a handful of cheaper NPT-threaded switches, but most are obviously GM-designed, not closing until more like 220 degrees (eek!). I'm planning to spend part of the afternoon pondering my taps to see what metric sizes can be easily adapted to, and possibly visiting an electrical store to see if they have any handy probe-type switches I can stick through the radiator fins like they use in some of the aftermarket fan controller kits.



Other suggestions I've found so far are all somewhat expensive for a project that started with a $25 junkyard fan - they include a Hayden 2-speed controller for about $60 shipped that some people claim to be unreliable; using a variable-speed controller to control only the high speed side (looks like at least $110 shipped); or a company called DCC that makes both 2-speed and variable stuff, starting at about $80 plus shipping. And of course, the usual aftermarket wet switches from sources like Hypertech or Painless seem to all start at about $40.

[1987cp]

Hmmm.....

FS270, $28.

Three-terminal (SPDT) thermal switch. Closes one circuit at 80 C (176 F) and the other at 90 C (194 F).

Only problem, I don't think I can buy or make a bushing to adapt its M14x1.5 threads to my available 3/8-NPT holes. Thinking I'd be stuck creating a complicated doohickey to run a modified 1/2" bushing into, such as something that would fit in the middle of a radiator hose, or else tapping out either the temp-light hole on the intake manifold or the electrical-sender hole on an iron waterneck.

Too bad I don't have a M14 tap handy ... I do have two M12 taps (1.5 and probably 1.75) .... they make M12 look like the biggest metric size I could reasonably tap into a 3/8" bushing, but I don't seem to be seeing any handy OE switches in a M12 threading.

[1987cp]

On the higher end of the price spectrum, I came across this article: http://www.fordmuscle.com/forums/coo...r-reviews.html

DCC appears to have some very nice variable-speed controllers for $130-plus, as well as a basic 2-speed controller for $80. Had the brand suggested by a guy I know is pretty careful about his stuff, says he lives in Florida and his system works great ... waiting to hear which specific kit he has.

[GM_Guy]

You are planning on using those temp sensors to trigger a relay, right?

When you figure out what switches you'll use, go to your local Napa and see what they have for adaptors, theres some funky stuff to be found. One of our local Napas has a heaping cabinet with various brass fittings and adaptors, you just need to ask for what you want. Failing that, a hydraulic shop is another great place to get stuff you didn't know existed (these usually cater to heavy equipment, so dont bother looking under automotive in the yellow pages).

Have you already run this fan? What sort of numbers are you getting on low setting and high setting? Something I'd want to know before picking sensors. If you've covered this already, link to thread please. What is your target temperature?

That last switch you posted sounds like the thing to use.

Alex.

[1987cp]

I wonder if a M14 sender has enough material to be reduced to 1/4-NPT .... I have a die and can do that for free ... wouldn't have to scare up a M14 tap and create a ridiculous arrangement to insert it in a 1/2-NPT hex bushing .....

[1987cp]

You are planning on using those temp sensors to trigger a relay, right?

When you figure out what switches you'll use, go to your local Napa and see what they have for adaptors, theres some funky stuff to be found. One of our local Napas has a heaping cabinet with various brass fittings and adaptors, you just need to ask for what you want. Failing that, a hydraulic shop is another great place to get stuff you didn't know existed (these usually cater to heavy equipment, so dont bother looking under automotive in the yellow pages).

Have you already run this fan? What sort of numbers are you getting on low setting and high setting? Something I'd want to know before picking sensors. If you've covered this already, link to thread please. What is your target temperature?

That last switch you posted sounds like the thing to use.

Alex.

Yes, relays R good. And I hadn't thought of a heavy equipment shop ... Gnater could probably help me find where to look for one of those ....


................



Um ..... Run? Numbers? The fan works on both high and low when connected to a battery in the driveway, if that's what you mean ......

[GM_Guy]

I mean what temperatures does low setting keep the car at, (just running some heavy wire and a big-ass switch). If you turn it on when temperature hits ~190, does it pull temps down quickly? Does it do anything? If you hit high speed, what does it do?

What I'm getting at, is low speed enough, if it is not, you might only end up using high speed in which case a single temp switch would be all you need.
I'm also getting at, if low speed is enough to cover 99% of your driving then a high speed turn on may be better suited to a higher temp (ie: 220º), rather than turning it on at a lower temp that is close to normal operating temperature.

Alex.

[gadget73]

you can do two speed switching with two relays. Somewhere in the long ago past I posted a schematic for the relay wiring. Basically one relay is power on/off and the othe relay is hi/low. I forget how I had it set up, but it involved a couple of diodes. It was quite honestly a lot of wiring mess for what I percieved to be no real benifit. I'd probably say try it on low speed and see how it does. If you need more cooling, wire it up to run on high speed.

[1987cp]

I mean what temperatures does low setting keep the car at, (just running some heavy wire and a big-ass switch). If you turn it on when temperature hits ~190, does it pull temps down quickly? Does it do anything? If you hit high speed, what does it do?

What I'm getting at, is low speed enough, if it is not, you might only end up using high speed in which case a single temp switch would be all you need.
I'm also getting at, if low speed is enough to cover 99% of your driving then a high speed turn on may be better suited to a higher temp (ie: 220º), rather than turning it on at a lower temp that is close to normal operating temperature.

Alex.

Aaahhhh... you're assuming I already have mounting brackets made and have begun on-car testing. There's some logic to your approach, though, and it's in the process of crossing my mind to do something along those lines.

Current thermostat is 180 degrees, don't remember if I mentioned that.

you can do two speed switching with two relays. Somewhere in the long ago past I posted a schematic for the relay wiring. Basically one relay is power on/off and the othe relay is hi/low. I forget how I had it set up, but it involved a couple of diodes. It was quite honestly a lot of wiring mess for what I percieved to be no real benifit. I'd probably say try it on low speed and see how it does. If you need more cooling, wire it up to run on high speed.

The relays are the no-brainer part, mang.

I've seen a couple of diagrams with anti-overvoltage diodes across each relay, and others that appear to lack diodes. If I were to go that way, it might end up helping that I have space for 1-2 diodes in my Windstar fuse panel ... just gotta visit a different Ford dealer to see if they can get me more terminals.


BTW, I've also gotten a handful of recommendations for variable-speed fan controllers. The logic in letting the fan start at a low speed and not run faster than needed is appealing to me. Here's a neato article you may have seen before: http://www.fordmuscleforums.com/cool...r-reviews.html

[gadget73]

The diodes across the coil are to keep the things from spiking the electrical system when they are de-powered. The coil in the relay will charge up like an ignition coil, and when the power is removed it will send a surprisingly strong jolt backwards through the system. The diodes are just there to short out the discharge.

[1987cp]

Ahhhh. I'd wondered where those alleged voltage spikes were supposed to come from.

Must be the same sort of deal in that diagram from RJM Injection Tech that shows a diode going from ground to the hot lead to the fan?

[Glen]

I just use a stick thru the rad. type, (Advance Auto $17.99) with a fan from a Linc. I run it on low speed and it has never had been over 200 - 205 deg. I have used it for a few years and it works fine for me.

[1987cp]

You were able to buy just a thermal switch with the radiator probe? I've not been able to find that yet, only kits that include extra wires and relay mounts that I don't really need.

[Glen]

Ya it is just a on-off switch with a probe. It has a temp adj. screw and I think only 2 wires. One for power and the other to the relay.I just let it run until it was at the temp. I wanted it come at, turn the screw until the fan came on. It is set for on at about 200-205, it turns off at about 190. Check at Auto Zone or Adv. Auto.

[1987cp]

Yes, but check them for what? The websites won't bring up anything like that unless it's a factory part and I know the application and description, and not all individual stores keep the same inventory. A brand and part number would be immensely helpful.