I have a spal fan, wired with a spal relay harness. It has been wired for 5 years and ran an worked fine. Now it wont kick on when the temp goes up. I have a manual "ground override switch" that I can flip on and all wrks fine. I figured the sensing thermostat switch was bad, I changed it, still will not start the fan. I have installed 3 different thermal switches and still nothing. I used 2 different spal ones and just now tried a less expensive one from Speedway...still won't start the fan when the temp goes up. I know I can just flip on the override switch but I would rather have the fan just come on when it is needed. I tend to foget to hit the switch until I see steam LOL I have another car with the exact same wiring system and it works fine, like I said this one USED to work fine. Any ideas? Thanks Dale
If the temp sensor switch is plumbed into a coolant passage, I'd check there to make sure you have a good ground, I just had an issue with that last week.
Do you have the override switch hooked up to kick over the relay or does it just kick on the fan? I'd check the relay otherwise.
The switch wire is attached to the terminal of the thermal switch, so it will ground the switch and starts the fan. Its like the thermal switch has lost its gnd, but it is just screwed into the manifold without any teflon sealant so the gnd should be there. The relay is good or the override gnd witch would not turn it on to turn on the fan
I have the exact same setup, maybe the thermal switch has oxidized and lost its ground, did you try removing the body from the port, cleaning the surfaces and reinstalling it, I t taped mine put it in, it didn't work pulled the t tape reinstalled it and it did, they are that touchy.
hmmm..... well it's definitely not a grounding issue then. Only thing I can think of is maybe there's a air pocket in the engine, which happens to be where the thermal switch is and is not registering the engine temp properly. Other than that, I'm out of ideas.
Test the intake to make sure it is grounded, I know that sounds stupid but is a long shot possibility. If the fan comes on with the toggle switch you know from where the toggle switch is attached ,to the relay, to the fan is fine. So you know you have a problem at the thermal switch itself. You changing that many switches and they all be bad, no way. But to cover all your bases also test the thermal switch outside the car, by heating it up, see if it trips. If the intake shows no ground, turn a few intake bolts.
I think I just figured it out, I'm not sure when it stopped working, but I know it did not work after I powder coated the manifold, I'll bet I got powder in the threaded hole so now I don't have a gnd except when I flip the switch. I'll get a big tap and run it thru the hole to get the powder out. Thanks for the help, sorry I did not think it thru enough before I wrote. I kept thinking why it would not work and remembered the powder coat job.
The inside of the intake bolt holes are going to be covered as well as the top surface. Your going to need to get some clean metal somehow. Maybe ground a carb stud, that kind of makes me cringe, but it's an option. Is the thermostat housing in the intake? could ground a bolt from that.
the switch should be either open or closed and since your running a wire to a switch to ground it, i would say the switch works the grounds side of the relay. meaning from a ground to the switch, FROM the switch to the ground spade of the relay and the switch just connects the circuit (which your manual switch is doing now). make sure the wire from the switch is grounded good.
the thermal switch is in the manifold, I could clean the threads and then run a gnd wire from the thermostat housing to a good ground, I think that would do it. thanks for your input crackerass54, and the others too.
Hi Dale,----you gonna be at LAR show fathers day???--------Don Hope you got the problem fixed by now!!!!
Hi Don, yes i am going to the LARS, leaving this Sunday AM, taking the long senic route. See you there! Check my blog of the trip each night at www.thedeuceguy.blogspot.com
Having the same problem with mine (I have a spal too). Used the search function and found this thread. I didn't realize the thermal switch was that touchy. thewildturkey46, did you get your problem taken care of?
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