Electric fan question

[Ken B.]

My 75 has run hot for a year or 2 so i installed a electric fan with has solved the problem.The thing that is happening now is, when i turn the car off the engine runs till the fan stops.I have it plugged in to the acces. terminal on the fuse box. I know that it probably needs a diode installed to stop the flow back to the box. Anyone have an idea on what kind or which diode i need? Thanks
Ken

[Michael W.]

Re: Electric fan question

The addition of an electric fan has not solved the basic problem, just masked it temporarily. Later C3s are not that difficult to cool properly so you may have a simple to cure problem at hand.

In any case, your electric fan should be wired from a switched 12V source on the fuse block so that when the key is in the off position, there is no power. I presume that you have incorporated a thermal switch into the wiring to turn the fan on and off, but some how have crossed the wires with the ignition.

[Ken B.]

Re: Electric fan question

The acc post on the block is a switched supply isn't it? And the electric fan is because of driving in traffic.Thats when it runs hot, on the road it is fine just don't like getting it high in the temp range. Way to much $ in the motor.

[Edward J.]

Re: Electric fan question

Ken,
Does Running a electric fan seems to correct the problem ,If so I would
check the clutch fan, spin the cooling fan, should show some resistance.I think the electric fan is a bad idea, the load factor to the orignal wiring and circuts could cause a problem down the road. like last post said its masking a problem.older radiators internal cooling veins tend to block with scale after a number of years. also the external cooling fins tend to build up debris preventing airflow problems.

[Michael W.]

Re: Electric fan question

The acc post on the block is a switched supply isn't it? And the electric fan is because of driving in traffic.Thats when it runs hot, on the road it is fine just don't like getting it high in the temp range. Way to much $ in the motor.

I believe it is switched, but there is still the primary concern that you have some how cross wired it with your ignition.

My moderately modified '73 has a 100% stock cooling system which has no problem keeping things under control- even in traffic with 100+F ambient temps.

[Ken B.]

Re: Electric fan question

Mike...2 wires...1 is power the other is ground.If you reverse them the fan just spins in the opposite direction.

[Michael W.]

Re: Electric fan question

2 wires to your fuse panel? Where are you grounding it?

[Ken B.]

Re: Electric fan question

1 wire to fuse panel..Other is grounded to the frame

[Michael W.]

Re: Electric fan question

If you turn your key off and still have power at the fuse box terminal, you have a problem right there. How this interrelates with the ignition problem might be with the ignition switch.

It really doesn't matter whether you have a fan or a simple light bulb in the circuit, it should go dead as soon as you switch off the key.