MattB

Okay, so im installing an E-fan today...

Im wondering if i can use the thermoswitch that turns the fan on in front of the radiator? the little fan...



circled in green is what supplies ground to my front fan. when the engine gets warm, the smaller front e-fan turns on. my question is can i run another ground wire to my big e-fan and use that to turn my big e-fan on and off?

-Matt

J-Rat

iTrader: (2)

There is a reason I didnt use that... Cant recall what it was. Maybe it was because it doesnt turn on untill like 207 or so (NZConvertible knows the exact figure),,,

MattB

can i buy another one at autozone or something that will turn on earlier? if i bought new theroswitch for my e-fan...where does it bolt in?

HAILERS

The fan water temp switch supplies a ground as long as the temp is below 207 degrees. More than 207degrees the ground signal is removed.

So you'd have to take into consideration that there will NOT be a ground signal being put out when over 207 degrees but WILL be 207 and under.

So whatever unit your using would have to be looking for a signal where a ground is removed not put on the unit. Make sense? Does to me.

J-Rat

iTrader: (2)

That would probably explain why I didnt use it..

deadRX7Conv

I don't have that. I'm wondering if I should you a different pump housing when replacement time comes.

Are you still planning on using the little fan? If not, find out what threadsize the housing is tapped for and search for other MFG temp switches that use the same thread. Sure beats having to drill/tap another hole.

According to Mazdatrix price list, the turbo uses a 207f switch, the nonturbo auto is at 195f. If you have an upgraded radiator, 195 degrees is a good temperature to switch the fan on.

MattB

ok so i went to autozone to get a new thermoswitch that went on at 185 degrees...and well......i guess that is a flow switch and detects when the coolant is flowing through the system. it sees when the thermostat opens (i have a 185 degree thermostat) and thats when it switches...i still wanna use it but is it possible?

EDIT: 2 seconds of reading online to find that the guy at advance was wrong...GO FIGURE...the guy at Autozone told me that it would take him a few minutes to look through his stock so i said ok and waited...but instead of looking he just told me to go elsewhere...THEY SUCK...and then i got my relay at Radioshack...10 AMP 12VDC...then i went to Advance Auto Parts and he told me that it was a flow switch...WRONG! ugh...now i have to find one before i can get my car on the road...stupid people...

deadRX7Conv

You want the fan switch to be higher then the thermostat. What you want to do is leave the thermostat mostly open and have the fan cycle. You don't want the fan to exercise the thermostat constantly by choosing a temp that is too low.
Also, an upgraded radiator will put less stress on the aftermarket efan(which one did you get?). IMO, the stock radiator is inadequate(especially if 15 years old and clogged). If the rad is inefficient, the fan will cycle too frequently and not last too long.

MattB

is it a problem that my rad fan turns on at 207 degrees if my thermostat opens at 195...or 185...im not sure...but its one of the two.

J-Rat

iTrader: (2)

Not a terrible problem, but like Hailers was saying, the stock sensor works backwards. It REMOVES the ground when over 207..

MattB

ok well i wired it up and it works wonderfully just need to get the wires tucked back where they arent seen, and tape over the solder joint. now im gonna go pick up a lower thermoswitch for it. something like 185 or 195. for now ill just drive around with it on constantly...

Aaron Cake

iTrader: (1)

You mean use adhesive filled heatshrink over the solder joint, right?

185 is also way too cold. The fan will be running constantly as soon as the engine wams up and will continue running with the car shut off for 20 minutes or so (assuming it is wired to constant 12V).

Summit Racing sells adjustable thermostats for about $20.

Also see http://www.aaroncake.net/rx7/efaninstall.htm

deadRX7Conv

How did you wire it? to the small fan? or independent with a relay?

Running constantly defeats the purpose of the E-fan. Constant load on alternator and constant fan running, IMO, is hack.

http://www.spalusa.com/fans/automate...cessories.html
http://permacool.com/Catalog/Cat_page19.html
http://www.flex-a-lite.com/auto/html...cessories.html
http://www.aaroncake.net/rx-7/efaninstall.htm

To use the stock thermoswitch, just wire your "relay's ignition on" into the positive power lead on the small pusher fan or its relay. This way, your high power aftermarket fan(with its own relay/fuse/wiring) won't overload the stock fan's wiring/relay, and it will switch on&off along with(or without if removed) the stock fan.

MattB

my wiring is through a relay. it goes battery, fuse, relay, fan....

and on the relay circuit it goes from that thermoswitch...(grabbed the ground from the small e-fan) and it has a constant 12V. so as long as that thermoswitch is over 207...the fan is running. hasnt been tested yet because i have to put my TID in. but when i remove that connector from the thermoswitch it turns on. thats a GOOD sign. what temp is the car supposed to run at? i know its a quarter up on my S4 gauge but what temp is that?

Aaron Cake

iTrader: (1)

That sounds like an acceptable setup.

The thermostat on the car opens at 84-85 C according to the FSM. Remmeber that it's the thermostat that sets the temperature of the car and not the fan. The trick to setting up the e-fan is to have it not fight the thermostat. There needs to be a hysteresys between the thermostat and fan so that the fan is not activated as soon as the thermostat starts to open.

Ricer240sx

iTrader: (3)

i got a thermal switch from a SR20 specialty shop called Heavy Throttle (http://www.srswap.com/) for like $30 bux, its really simple to hook up, it comes with a wiring diagram and is very streight forward and the temp sensor just attatches to the radiator and works like a charm!!! only problems i had with it were from me not setting the dial at the right spot lol! but yeah, i highly recomend it!!!

deadRX7Conv

Glad to see that you used the fuse/relay with your wiring. I'd have to look at your wiring since I don't understand how you're "triggering" the aftermarket fan.

Also, does your car have an airbag? Seems that Mazda used ground switching and power switching for the stock e-fan relay depending on years/options/transmission.
Does your stock e-fan have power but no ground when vehicle is off(no key in ignition)? or ground with no power?

Also, the stock temp switch at 207F is not too hot. The sensor placement is in an optimum location. The radiator is cooler and a sender mounted @radiator would need a lower temp setting for the same effect.

MattB

so from what im hearing my setup now should be all set right? the stock E-fan in front of the rad has power but no ground when the car is off...since i knew that the thermoswitch somehow gave that fan ground at 207 i took that ground and spliced it too my relay. when it sees ground, it activates the coil, which sends power to the fan. ill draw a diagram up later but i gotta head to my girlfriends house right now...


NO AIRBAG, by the way....



SO AM I ALL SET?


thanks,
-Matt

deadRX7Conv

The stock thermoswitch does not give the fan ground. It can't handle the fan current flowing through it.
The thermoswitch gives the RELAY ground which allows it to trigger full ground flow to the efan. Its the relay thats carries the load.

That same relay, triggered by the ground thermoswitch, can provide either power or ground to the stock e-fan depending on year/trans/model. If you haven't, please make the effort to test your e-fan for power or ground with the key off. Don't trust hearsay.

It does sound like your good to go. Using the underperforming factory wiring to trigger your aftermarket relay/fan is primo. This way there is only a minimal load added to the factory wiring.
Plus, the A/C will also trigger the fan(great in the summer or if pre-cooling the car prior to a drag). A fused override switch can also be used to 'anticipate' extra cooling if you don't have A/C.

Let me know how well your system works when its all finished. My waterpump has a leak and I'm might move to a housing with a switch to make my E-fan install look more OEM. I don't care for some aftermarket externally mounted(stuck to radiator fins) thermoswitches which fail quickly because of the elements. An OEM threaded temp switch is the best way to go.

MattB

yeah i know how the relay and all that works now...i didnt until yesterday when i just read for a while. i basically went off aaron cakes install schematics. they work!


but...i had ac but took it out. so if i turn it on...even though it isnt there...will that fan turn on?


my system seems to be running a bit cooler than it did...of course it is about 10 degrees outside so that might have something to do with it...

tomorrow morning ill go outside and take some pictures of my wiring but for now here is my diagram



now i still dont completely understand how that ground works through the thermoswitch since people are saying at 207 degrees it takes away ground...but it works...and thats what matters...

HAILERS

***************now i still dont completely understand how that ground works through the thermoswitch since people are saying at 207 degrees it takes away ground...but it works...and thats what matters...************************************

Just look at the 1987 FSM schematic of the fan circuit on page Bc of the schematics.

The water temp switch circuit is connected to ground until above 207 degrees. Then the contacts in the switch open and now there is no ground to the Electric Fan Relay.

So now the Electric Fan Relay relaxes and in turn MAKES a circuit thru its contacts connecting the cooling fan itself to the Control Unit which in turn puts a ground on the Cooling Fan and the fan now runs IF the key is to ON.

On a car with a working stock electric fan you can prove this to yourself. Just put the key to ON and pull the connector off the water thermo switch. The fan WILL now run. Put the connector back on and now it will stop running.

Or, with the key to ON pull the METER fuse. The fan WILL run because you took the power source away from the Electrical Fan Relay and made it relax causing the contacts to close and make a ground for the Cooling Fan Motor, much like what you did when you remove the plug from the water temp switch.

In other words stare at the schematci Bc of the 87 FSM and you WILL understand.

MattB

i get that but how does the fan run without ground then...?

deadRX7Conv

The fan has ground provided by relay----THE THERMOSWITCH IS NOT CONNECTED TO THE FAN, its connected to the relay that provides the ground.

HAILERS

I'll jpg you a copy of the fan schematic later today so you can see.

The ELECTRICAL FAN RELAY's contacts are not MADE with the key to ON and the water temperature less than 209 degrees.

Above 209 degrees the ground from the water temp switch goes away which in turn makes the ELECTRICAL FAN RELAY relax and the contacts close to form a ground for the fan motor.

driftin8ez

I cant seem to find any for cheaper than $50 on summit. Do you have a link or part number.