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1078 fording fan switch issue
- Thread starter Boisemed
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snowtrac nome
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no its something with the thermo control mine stayed on all the time to I forgot what I did to fix it but it was an easy fix.
coachgeo
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following.... mine is on all the time too.... but then again with engine off fan won't turn so I think that is other issues
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First, the way the fan works is a little counter-intuitive. When the truck is off (no air pressure), the fan is engaged, by default. When you turn the truck on, the fan clutch switch in the upper radiator tube is a Normally Closed circuit, which turns on a solenoid and allows air pressure to disengage the fan clutch. So it's normal operating state is solenoid powered, clutch pressurized, and fan off. When that coolant switch hits 210 Farenheit, the switch opens, the solenoid shuts off, pressure is removed from the clutch line, and the fan re-engages.
I haven't looked at the wiring diagram (you should, they are in the back of the TMs), but I assume the fording switch is an alternate circuit path to force the solenoid to stay powered, and thus force the fan to stay disengaged. Again, without having seen the wiring diagram, I don't think there would just (alone) be a way to wire the switch backwards, have a faulty switch, etc. that would result in totally opposite behavior (e.g. switch on keeps solenoid off and fan engaged, switch off keeps solenoid on and fan always off). If other components were also wired incorrectly or malfunctioning, you might be able to get other behaviors.
That said, my truck came where someone had taken another one of the overheat warning coolant switches (look the same, but are Normally Open and close at 230 Farenheit) and installed it in the position for the fan clutch switch. The resulting behavior was that the fan would have been always on, and turn off at 230 Farenheit. However, my fan clutch was broken and stuck on anyway, too.
I haven't looked at the wiring diagram (you should, they are in the back of the TMs), but I assume the fording switch is an alternate circuit path to force the solenoid to stay powered, and thus force the fan to stay disengaged. Again, without having seen the wiring diagram, I don't think there would just (alone) be a way to wire the switch backwards, have a faulty switch, etc. that would result in totally opposite behavior (e.g. switch on keeps solenoid off and fan engaged, switch off keeps solenoid on and fan always off). If other components were also wired incorrectly or malfunctioning, you might be able to get other behaviors.
That said, my truck came where someone had taken another one of the overheat warning coolant switches (look the same, but are Normally Open and close at 230 Farenheit) and installed it in the position for the fan clutch switch. The resulting behavior was that the fan would have been always on, and turn off at 230 Farenheit. However, my fan clutch was broken and stuck on anyway, too.
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Thanks Awesomeness it is weird. I know the fans work normally when driving as they come on when she gets hot (solenoid must work). When driving and I flip fan switch to test they come on and stay on till I shut the switch off! must be alternate pathway as you suggest I have to download TM's and look or maybe its the switch like you said!! It came to me this way as well