Thermofan Relay Help Please

[schtein]

Gday guys,

I dont have a skyline, but i was hoping that someone on here might be able to help me. The thermofan on my 300ZX TT seems to have a life of its own, sometimes it runs and sometimes it wont. Today it wasnt running but after i turned off the car and restarted the thermofan ran non-stop the whole time i was driving it and it continues to run on a cold engine when i turn the key.

Im guessing that its the relays as they were installed. I was hoping that some kind person could check these over for me. There are two relays, one white and one black.

White:

30 - Black 30

85 - Thermo temp sender

86 - Merges with Black 85 to Thermo switch

87a - Thermofan +

(Thermofan - is grounded)

Black:

30 - White 30

85 - Merges with White 86 to thermo switch

86 - Ground

87 - Battery +

diagram:

Does this seem right? Any help much appreciated. It is a Spal 16" thermofan.

-Martin

If its not this ill turn my attention to the switch

[blind_elk]

Not sure why you have 2 relays. Ordinarily, it would be set up with:

Pin 30 = +12V (battery)

Pin 87 = +12V -> fan -> earth

Then depending how the thermo switch works:

Pin 85 = thermo switch -> earth

Pin 86 = +12V (IGN)

or

Pin 85 = +12V <- thermo switch

Pin 86 = earth

[QWK32]

first of all without a pic of the diagram on the side of the relay, all we can go off is what the pinout of a relay should be. and also from the diagram the only way it will work is if the thermostat (sender) is a Normally Closed switch, switching ground.

- the way its wired there, if the switch is on (purple wire fed +ve), and the thermostat is below its switching temp, the fan wont run, untill it reaches its switching temp.

- if the switch is turned off (purple wire not fed anything) but the thermostat is at switching temp, it wont run. must be so you can turn the fan off anytime you want.

- you need the switch on and the thermostat at its switching temp for the fan to run. but it should switch off below a certain temp.

so... from what you have described is happening i would say that your thermostat (sender) has shit itself and isn't and sending the ground signal to the white relay once your water temp goes below its set temp.

you need 2 relays so you can use a manual switch to "override" the thermo fan from running it you want. it does seem like a wierd way to wire it but looks like its the way it has to be with the temp sender your using.

[schtein]

Very informative post QWK32, thanks a lot mate

[tridentt150v]

Not sure about that, if you use one relay and then take the thermofan power from the top one [black one] at 87a and then install a switch in the power lead to the fan, you only need the one relay.

Its exactly the same for driving lights, on/off switch and another live switch to the low/high beam.

[2rismo]

I run a pair of thermo fans that I can switch on in two ways.

1/ Temperature controlled - automatic

2/ Manually switched.

The temperature controlled automatic method does what it should and switches the fans on or off as it sees fit and the manual switch turns the fans on regardless of what the temp is.

It runs one relay for the lot.

[juggernaut1]

SPAL wiring diagrams:

http://www.spalusa.com/fans/automated/tech...185FH-195FH.pdf