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changing over to toggle switch for fan

2K views 4 replies 4 participants last post by  NEW INTERIORS 
#1 ·
My current electric fan with a resistat (control that switches the fan on a designated temp and off when it cools down) is malfunctioning. I am going to install a toggle switch that is manually operated from inside the cab. Can I just take the 'hot wire' from the resitat and hook up the positive wire on the fan and run it back to the toggle switch? Where does the ground wire go?
Thanks
 
#2 ·
You could probably get away with that for a while, but chances are eventually the toggle switch will fail because of the load involved. The proper way to do it is with a 30 or 40 amp relay and a toggle switch. The toggle switch will power the relay coil and use a set of normally open contacts of the relay to run the fan. The below diagram shows two fans, but just delete one fan for your application.


Vince
 
#3 ·
Also watch to see if the engine runs too cool. This can happen. It can get so bad that you have to change the spark plug heat range. Otherwise the car will refuse to start after a time (4-6 weeks) and the only thing that cures the ptoblem is new plugs. Been there, years ago with a GM "J" car.
 
#4 ·
BOBCRMAN@aol.com said:
Also watch to see if the engine runs too cool. This can happen. It can get so bad that you have to change the spark plug heat range. Otherwise the car will refuse to start after a time (4-6 weeks) and the only thing that cures the ptoblem is new plugs. Been there, years ago with a GM "J" car.
That happened to me right after I installed my crate 350 in my frame. I wired it up to run it and once every other day would crank it up and give it a few revs. That went on for several weeks then all of a sudden it wouldn't start. Pulled the plugs and they were all sooted up. A new set of plugs fixed it right up.

Vince
 
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