Quick E-Fan Question

[BigHairyMonkey]

I re-did my fans but after undoing all the wiring i lost the schematic to incorporate the temp sensor into the 5 prong SPDT relay. The way i have it wired right now is

#30 - 12v To battery Fused
#87 - 12v to Fan
#85 - Ground
#86 - Acc lead

I have a temp sensor by the t-stat w/ 1 wire coming off of it, i remember from before i had all 5 connections on the relay used up (so obviously i have to incorporate 87a as well). Could someone that actually knows their wiring (unlike me ) tell me what to put where so that the fans kick on based on the switch and not on acc power. Thanks

 

[BigHairyMonkey]

anyone ? jrich?

 

[HISSIN50]

87A will likely not be used. When the relay is at rest, 30 and 87A are naturally connected. There's no need to use this unless you use multiple relays for cutting one fan speed off as one comes on (if you need such a schematic, I drew one up for Fett awhile back and can email it to you).

Do you know if your temp sensor sends ground to the relay to make the fan come on? If it only has one wire, that's likely the case (the 'other wire' is the fact that the sensor is grounded, so as the sensor achieves the target temp, the output wire sends a ground signal to energize the relay).

If this is the case, you will need a blocking diode on this wire. Then run it to 85. You will have to undo the existing 85 ground-wire if you have it permanently grounded (or the fan will run non-stop with the key-on).

FWIW, when 86 sees 12 volts and 85 sees ground, 30 connects to 87. Just so you know what's going on if you were unsure.

Good luck.

 

[jrichker]

This version of the fan controller will continue to run the fan after the ignition switch is turned off, just like most new cars.

To allow the ignition switch to control the fan so that it does not run when the ignition is off, connect the relay contact #86 to the red/green wire on the ignition coil or to the red/yellow wire on the coolant level sensor.

 

[BigHairyMonkey]

the temp sensor only has 1 wire coming off of it. So let me get this straight i just unhook the ground off the relay and replace it with the temp sensor wire so that it will act as the ground as soon as the temp gets to a certain degree?

 

[HISSIN50]

the temp sensor only has 1 wire coming off of it. So let me get this straight i just unhook the ground off the relay and replace it with the temp sensor wire so that it will act as the ground as soon as the temp gets to a certain degree?

That's where knowing the type of switch comes into play. None of us can know. I made an educated guess based upon the info given. If that is the type of switch you have, then that should work. You'll note that your set-up will be wired very much like Jrichker's diagram (sans the positive relay-coil power source).

 

[BigHairyMonkey]

im gonna try it like that *crosses fingers*. thanks guys

 

[BigHairyMonkey]

yea i tried swappin the ground w/ the temp wire and the fans didnt kick on at all so thats not how to wire it..

 

[HISSIN50]

What resistance does your temp sensor read when it's at its target temperature?

You might need to affix a ground wire to the sender body if you used thread sealant on the threads (the sensor achieves ground via its mounting and thread sealants act as an insulator). This can and will keep a ground-passing sensor from working properly (I've had to mechanically ground sending units myself).

Good luck.

 

[BigHairyMonkey]

Well it worked up until i undid the relay a week ago to clean up the wiring so nothings changed.. the sensor is not new its been on the car for years. And i have no idea what the ohms are at target temp i just know the fans used to click on at around 3 bars on the stock temp gauge.