Fan Issue still here....

Pacco · #1 (**permalink**) 05-26-2008, 05:06 PM

Puller fan kicks on with the turn of the ignition switch. Thus, not allowing the engine to reach proper running temp. I am by no way an electrician. Used circuit tester, the type that lights up either green or red. Using a manual switch. When switch is in the on position the tester light shows a red light when both switch post are touched using the tester. I can pull the 25amp fuse and the fan kicks off. What am I missing?????????

vector1 · #2 (**permalink**) 05-26-2008, 05:25 PM

thermostat regulates your engine operating temp, radiator just dissipates heat with the aid of the fan.

Dwight · #3 (**permalink**) 05-26-2008, 05:36 PM

Do you have a toggle switch to turn the fan off? What temp. thermostat do you have? Most need a 185 to 195 degree thermostat. Your engine needs to run hot enough (200 - 210) to burn contaminants out of your oil.

Dwight

bigrob · #4 (**permalink**) 05-26-2008, 08:45 PM

If you cannot resolve the issue of the fan staying on all the time, you can always just wire it straight to the power and the toggle as on and off, eliminating the thermostatic feature......but if you do this, MAKE ABSOLUTELY SURE you watch your temp gauge and get the fan on when it is needed!!! A good rule of thumb would be....as soon as the motor hits operating temp, put fan on and leave on in stop & go traffic. Once on the highway, or road where your gonna keep a steady, relatively fast speed with out stopping, you can turn it off. But still always monitor your tremp gauge.

Barnsnake · #5 (**permalink**) 05-26-2008, 09:53 PM

If your engine is not reaching operating temperature, the problem is with the thermostat.

Here's the way I prefer to wire the fan circuit:

The fan is controlled by a relay that connects the fan + to the battery +. The other side of the fan is grounded. The relay connector has two large wires, one goes to the battery via a heavy fuse, the other goes to the fan. Power the trigger side of the relay with switched power. The fan relay is triggered by grounding the wire that goes to the temperature switch (the switch goes to ground when it's specified temperature is reached). You can use a toggle switch on the dash to "bypass" the temperature switch and turn the fan on regardless of temperature. Wire one side of the switch into the circuit that goes to the temperature switch on the engine and wire the other side to ground.

With this system the fan runs only when the engine reaches the thermal switch temperature, or when the override switch is flipped. The fan stops when the key is turned off.

vettestr · #6 (**permalink**) 05-26-2008, 09:54 PM

Many fan circuits are wired hot and the ground is added/removed with the switch and temp sensor. If yours is wired this way here is whats happening. Key supplies B+ and then the temp sensor reaches trip point so enables the ground and fan turns on. If you want to turn fans on before it has reached the set point you turn the toggle switch and it supplies the ground source so fans come on.

I think you have a switched ground system and something or somebody has defeated the temp sensor, so it is grounded always and the fans always run. Get a volt meter for as little as ten bucks so you can check polarity and see if voltages are present to be able to check things out.

With the tester/light you now have you can not test a negative switch but doing test below will not hurt tester of the circuit, it simply will just show red all the time. You could use a known B+ source and sw. but much easier to walk ya through a VOM.

I think you have a bad sensor or if adjustable it is tweaked as low as possible and always on. Fix the sensor and you will be good to go.... Of course this is only cause I stayed in a Holiday Inn last PM

Pacco · #7 (**permalink**) 05-27-2008, 06:55 AM

I switched from a 160* to a 180*. Put in a new mechanical temp gauge. On/ Off switch on the dash for the fan. I think it is a Classic Roadster wiring. When I pull the fuse out the temp does increase to a normal operating temp. Otherwise it peaks at 170*.

Ron61 · #8 (**permalink**) 05-27-2008, 07:12 AM

Pacco,

If you can get to your fan and the wiring, try to follow it and see where it connects. I had twin pushers in my Classic roadster and an adjustable thermostat switch which I set on the highest setting, but still had to turn the fans off on normal days or mine would never get above 180. I was tracing the wiring one day and found it was all messed up, so I just cut it out and got some new wire and ran my own from the fans to the controller and also to my dash on/off switch. I never had a problem after that with them coming on at low temperatures.

Ron

vettestr · #9 (**permalink**) 05-27-2008, 07:27 AM

do you have a meter or a test light? By test light I mean type with a probe oe ice pick that has 1 wire you connect to ground. When you touch probe to a hot wire it lights up?

Pacco · #10 (**permalink**) 05-27-2008, 03:02 PM

Vettestr, I do have a tester like the one you have described an ice pick type. Any ideas? Thanks!!!!!

Ron61 · #11 (**permalink**) 05-29-2008, 04:20 AM

I think you have a switched ground system and something or somebody has defeated the temp sensor, so it is grounded always and the fans always run. Get a volt meter for as little as ten bucks so you can check polarity and see if voltages are present to be able to check things out.

Vettestr is most likely correct with the above statement. But if you do have a relay, make sure that it isn't closed all the time, either by burned contacts or another ground feeding to it. Also it is possible as this happened to me once that the temp sensor can go bad and short. I found my problem in about 10 minutes with a volt/ohm meter and just replaced the sensor and that was the problem. I also had a manual switch but it was ok.

Ron