Cooling fan constantly running

[onlysardegna]

Hello, my cooling fan just wont turn off. The only way to stop it is by disconnecting the battery! Any help as to what to do and how to fix is very welcome! Thanks!

[AriK]

There's a fan temp switch at the bottom of the rad, driver's side. It could be defective or the terminals are bent out of shape and somehow making a connection. Auto Ricambi sells replacement switches for cheap.

[onlysardegna]

There's a fan temp switch at the bottom of the rad, driver's side. It could be defective or the terminals are bent out of shape and somehow making a connection. Auto Ricambi sells replacement switches for cheap.

Thanks much AriK! I assume with rad you are talking about the radiator? Would that be that big plug going in to the radiator system or is it a regular switch? I just checked and could only find this plug with cable going in to the radioator (I am not talking about the fan.. correct? Sorry, I am so not a technician .

[RRoller123]

Yes: Radiator, temp switch located lower driver's side, rear of radiator, large switch with two leads going to it. If it is shorted internally, i.e always closed, making the connection, then the fan will run all the time that the battery is connected, even when the ignition is off.

Try disconnecting one of the wires and the fan should go off. If not, the switch has somehow been bypassed. The switch should be open (~infinite resistance) when cold, and closed at about 195 DegF Hot. You can measure with the switch still installed, just disconnect both wires and disconnect the battery, because one of those wires is permanently hot (ALWAYS has voltage on it).

Pete

[onlysardegna]

Yes: Radiator, temp switch located lower driver's side, rear of radiator, large switch with two leads going to it. If it is shorted internally, i.e always closed, making the connection, then the fan will run all the time that the battery is connected, even when the ignition is off.

Try disconnecting one of the wires and the fan should go off. If not, the switch has somehow been bypassed. The switch should be open (~infinite resistance) when cold, and closed at about 195 DegF Hot. You can measure with the switch still installed, just disconnect both wires and disconnect the battery, because one of those wires is permanently hot (ALWAYS has voltage on it).

Pete

Thanks Pete!! Great help!! I will try to do what you suggest! hope I'll succeed! thanks again!!!

Ingmar

[AriK]

[RRoller123]

Yep, this little critter closes the connection to ground, completing the circuit and powering the fan. Which is why one side is always hot.

I suppose it is possible that your car has a "Fan On" bypass switch, a lot of cars were fitted up with these when/by prior owners couldn't figure out solutions to the cooling problems, which were nearly always the result of incorrect bleeding of air from the system ("burping").

My car came with one of these switches (and trapped air too). Under the dash, near the driver, is the normal spot to install one, so that it can be reached easily. Once in awhile, but very rarely, I will accidentally turn it on and the fan will run. I left it installed because I would likely create more trouble than it is worth if I tried to take it out, rather than just leaving it alone.

[onlysardegna]

Yep! That's exactly what I found. I will have to work on it tomorrow!

(In case it is not what roller suggested a bypass switch. That would be nice for me if I could just flip the switch!!)

Thanks for the pic and clarification Pete.)

[onlysardegna]

Yep, this little critter closes the connection to ground, completing the circuit and powering the fan. Which is why one side is always hot.

I suppose it is possible that your car has a "Fan On" bypass switch, a lot of cars were fitted up with these when/by prior owners couldn't figure out solutions to the cooling problems, which were nearly always the result of incorrect bleeding of air from the system ("burping").

My car came with one of these switches (and trapped air too). Under the dash, near the driver, is the normal spot to install one, so that it can be reached easily. Once in awhile, but very rarely, I will accidentally turn it on and the fan will run. I left it installed because I would likely create more trouble than it is worth if I tried to take it out, rather than just leaving it alone.

I will see whether I have that~! I would actually like to find that. Would make things easier for me as a non technician. I just always loved the style of the car and luckily never had big technical issues! Thanks much for the hint RRoller!!