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Re: Two speed radiator fan Posted by Ari [Email] ![]() ![]() In Reply to: Two speed radiator fan, Vladimir, Mon, 16 Jul 2001 12:32:58 Members do not see ads below this line. - Help Keep This Site Online - Signup |
In reality, the fan has two speeds - normal and slow.
In the case of a two-speed fan, there is a two level thermoswitch in the radiator. When the radiator temp exceeds the first setting (around 90C, I think), a switch closes and supplies 12 volts through a resistor to the fan. Because of the voltage drop of the resistor, the fan runs slower. When the radiator temperature exceeds the next level (110C, I think), the second switch closes, and essentially shorts out the resistor.
Look at your fan to see if there is a resistor there. It would be a long rectangular metal device, usually gold-colored, mounted right on one of the fan supports. If there is no resistor, then you have a one-speed fan.
All a two speed fan does is turn the fan on slow at a cooler temperature. Frankly, I think it's more trouble than it's worth. If you have a single speed fan and you want better cooling, just install a lower temperature radiator fan switch. The fan will come on full bore, just at a lower temperature. The typical low temp fan switch comes on at 82C, instead of the 89 or 90 of stock. The switch is pretty standard, it just has two contacts.
So - the normal operation of the fan is with no resistor. A resistor is inserted to make the fan run slower, primarily to save power, not the fan. The fan can run at high speed (actually normal) all day long.
If you already have a two speed fan, the solution is the same. You can get a lower temp radiator fan switch - 82 and 100C.
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