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Radiator fan running all the time

4144 Views 11 Replies 4 Participants Last post by  forumoto
Hi Guys, my roadster has been off the road for a couple of years and I have started to fix her up. However the Radiator fan is constantly running once the battery is connected. Obviously this drains the battery,
The coolant temp sensor seems ok as the resistance changes with temperature and was replaced not long before being parked up.
When running turning the AC on Increases the fan speed. Apart from putting a manual sw into the circuit I'm not sure where to look next.

Any ideas guys?
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I’ll need to look at the schematics to me sure, but I can think of a few things that can cause this-

The temperature sending unit is flaky and telling the SAM that the coolant temperature is hotter than it is in reality.

There is a wiring or grounding problem that’s resulting in wonky readings.

Coolant levels are low and there is an air pocket that’s causing strange temperature readings.

The cooling fan relay is sticking.

I’m not home today, but will have a look at the schematic when I get home.
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You are working on a 451 ICE, correct?

If yes, the relay is built into the SAM. There isn’t much that controls the operation of the fan, so I think probably the relay contacts are stuck shut. What do you think?

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In my experience, wires seldom go bad unless they are being flexed or exposed to water or other chemicals. If the fan is running, the wires to the fan are ok (complete circuit). It might be worth checking the ME-SFI module to see if it got wet before digging into the SAM.
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