They will turn on as soon as I turn the heat on regardless of coolant temp. I've seen them run with coolant temps as low as 129°F. The default temp is 231°F according to my local Ford dealer.
99 Taurus cooling fan runs only when heater is on.
- Thread starter JN94
- Start date
Sounds like your thermostat is also stuck open. What new thermostat did you use
Unfortunately it was a Murray from O'Reilly's. Only thing available local to me. If I unplug the fans , the heater will run me out of the car on low. Currently viewing live data and seeing a coolant temp of 201°F with the fan unplugged.
First troubleshooting step I would take would be to see if the radiator fan power supply wires have voltage at the fan relay terminals while the fans are running. If yes, then I would suspect a shorted connection somewhere. If no, then I would suspect a rewiring job. Next I would pull the heater blower fuse/relay as it sounds like radiator fan operation is simultaneous with heater blower operation. That circuit might be the source of the power.
And yeah, it sounds like a problem with the thermostat. If you could cool an engine by just blowing air over the surface there would be no need for a radiator.
And yeah, it sounds like a problem with the thermostat. If you could cool an engine by just blowing air over the surface there would be no need for a radiator.
I'm starting to think it's most likely a wiring issue. Unfortunately I'm partially colorblind and wiring isn't my specialty because of that.
I'll swap it out with a new one.
They will still operate on low but only when the heater is turned on.
Yes.
I'm starting to wonder if I may have a bad cap on the coolant reservoir , which is making the car think it's hotter than it actually is by not holding the correct pressure. I noticed a hissing noise last night from the reservoir after the engine was shut off.
That would be confirmed or disproven by looking at OBD live data.
The point I keep coming back to is that someone has hotwired it or otherwise there is a problem with the wiring. There is no way the fans should run at all with the fuse and/or relays removed.
The point I keep coming back to is that someone has hotwired it or otherwise there is a problem with the wiring. There is no way the fans should run at all with the fuse and/or relays removed.
I agree that something has to be wrong somewhere in the wiring. My next question is , why is this issue just now occuring ? I've had this car for almost a year. The previous owner didn't have this issue.
Just a wild guess but maybe the AC pressure switch stuck in a closed position? Maybe try disconnecting the connector? It should be on one of the AC hoses near the accumulator.
Check for power at the large terminals in the relay block if you have power at both with no relay installed you may be dealing with a short in the fuse box.
