radiator fan has a mind of its own

[namancivicdx]

I have an '86 Honda Civic Dx.
Runs in red.
Had thermal sensor replaced, had a t-stat changed. And the fan is possessed. It runs at the strangest times.
It'll work. Then it won't. It'll work...
Etc.
Lately, it's been working when the key is at the 1 position, or off. Pull the key out...it's running (until the car is cooled down).
Turn the key to II or III and it shuts off. This is after idling for maybe 5-10 minutes, when the needle is spiked to the red. But the other day I could get the car to idle, start to heat up and then have the fan kick on. As it's supposed to do.
*shrug*
This after the mechanic i was working with "energized" the new thermal sensor. Now it just idles and heats up and heats up and even while driving. It continues to boil as with my temper.
Should i just design a toggle switch for it?
Would it be an easy operation?
Does anyone have a clue as to what I am talking about?

[tetraruby300]

I don't have a lot of experiece with these Hondas, just bought one less than a month ago. Your idea of simply putting the fan on a toggle switch is good except e-fans generally draw quite a few amps - meaning you'll need a beefy switch and some heavy guage wire. A similiar idea is to do what you're saying but install a relay close to the fan and then run lower guage wire up to the dash. You could then somehow wire it into your ignition so it would turn on when the key is on and stay on untill the key is in the off position. My $0.02. Although the temp running so hot is a bit of a concern. Your T-stat maybe kaput. I've seen new t-stats not work correctly...or at least consistently.

[cvcc_wagon]

firstly your fan will not fix your cooling problem, if it is getting that hot so quick you have other problems. i have had overheating problems in the past (and present) so i just bridged the two wires that go into the sensor so the fan is on all the time, the car still heats up at times but that is cause by other things. are you sure your coolant is topped off? if you get a small air pocket in the system it will eventually work it's way to the water pump and that will completely stop the flow of coolant through your engine. a bandaid fix for this if it happens to you in traffic or something is to turn on your heater, it not only acts as another radiator for the heat, it also introduces a little more coolant into your circulating system and help prime the pump and get things moving again. what would cause you to lose coolant (other than an obvious leak) would be a bad head gasket, coolant basically slowly leaks into the combustion chamber. a head gasket that is nearly blown will also make it overheat because when there is nothing blocking the hot gases and flame from the coolant it heats up much more quickly.

quick check (that any mechanic should have picked up on) is to see if your oil looks grey and foamy, just pull of the filler cap and look at the bottom side of it and inside the valve cover. if it is grey and foamy you have coolant in your oil and the gasket is blown.

[namancivicdx]

Okay...I'll check the oil.

As for heating up fast:
I didn't mention that this car is only used as transportation to and from work. Roughly, a 15 min drive. It is at the end of this drive that the needle is SPIKED.
The car was cooled down only half an hour after arriving home when I tried to get the fan to work again. So after 5-10 min of it creeping into the HOT area, did the fan only kick on with the key in the OFF pos. Still I got it to work somehow???

This Heating problem seems to be fixed by the fan. When(?) it works, the car runs fine.
Could this actually be a short in the system?
Even though the Thermal Sensor plug is receiving power?

[cvcc_wagon]

well i that is a possibility, i would just bridge the sensor wires and have it run all the time to see if it solves your problem, if not looks elsewhere