Radiator Fan Problem

[burnettdylan]

06 4.0, coupe, automatic. My radiator fan refuses to turn on, and it's not a relay or fan motor problem. After hot-wiring the wiring, it all works fine, but I don't know what else could be causing the fan to not turn on. If anyone has any ideas please let me know.

 

[Dino Dino Bambino]

If the fan turns on when you switch on the AC, but doesn't turn on when the coolant reaches a predetermined temperature causing the engine to overheat, the likely culprit is a bad ECT sensor. One way to confirm that is to see if the fan turns on the moment you disconnect the wiring harness from the sensor.

 

[burnettdylan]

If the fan turns on when you switch on the AC, but doesn't turn on when the coolant reaches a predetermined temperature causing the engine to overheat, the likely culprit is a bad ECT sensor. One way to confirm that is to see if the fan turns on the moment you disconnect the wiring harness from the sensor.

It doesn't turn on when the AC is on either.

 

[Racer47]

just a guess here...the fan has 2 speeds, are you getting high speed when you hot wire it? or can you get low speed too. Maybe the car is calling for low speed, which isn't working but high speed does.

 

[burnettdylan]

just a guess here...the fan has 2 speeds, are you getting high speed when you hot wire it? or can you get low speed too. Maybe the car is calling for low speed, which isn't working but high speed does.

I'm guessing it's sending it straight into high speed, but before I hot-wired it, the fan wouldn't turn on at all, and the only reason I realized was that the coolant was gurgling as soon as I parked my car.

 

[08TorchRedShelbyGT500]

How many miles are on the car?

 

[burnettdylan]

View attachment 114920

How many miles are on the car?

Around 164,000 miles

 

[08TorchRedShelbyGT500]

Around 164,000 miles

My guess is the fan cooling assembly is failing, and the low-speed setting has failed altogether. The gurgling is due to overheating because the low-speed fan isn't working at all. The high-speed fan should rarely come on if at all, so if yours is, you are overheating, and the low-speed fan isn't working.

 

[08TorchRedShelbyGT500]

Also, disconnect the harness connector from the fan assembly and look at the inside of the connector. The pins shouldn't show any signs of heat or melting. If that fan motor has seen its better days, and it is struggling to run and is drawing a lot more current to run, it could well melt the low-speed resistor pack and or harness connector to the fuse/relay box.

When I replaced my Fan assembly with a Ford Performance 7-blade 2013-2014 Fan assembly, I checked my connector, and it was fine. I also installed the WireEverything dual relay 8-gauge wire harness to eliminate all these issues. And my car only has 12,000 original miles. I did all this to make sure this common issue doesn't affect my car in the future. I also reset my low and high speed temp on settings to 206(Low) and 216(High) with a SCT tuner.

 

[burnettdylan]

Also, disconnect the harness connector from the fan assembly and look at the inside of the connector. The pins shouldn't show any signs of heat or melting. If that fan motor has seen its better days, and it is struggling to run and is drawing a lot more current to run, it could well melt the low-speed resistor pack and or harness connector to the fuse/relay box.

When I replaced my Fan assembly with a Ford Performance 7-blade 2013-2014 Fan assembly, I checked my connector, and it was fine. I also installed the WireEverything dual relay 8-gauge wire harness to eliminate all these issues. And my car only has 12,000 original miles. I did all this to make sure this common issue doesn't affect my car in the future. I also reset my low and high speed temp on settings to 208(Low) and 216(High) with a SCT tuner.

View attachment 114922

Do you know where I can find the connector in the car?

 

[08TorchRedShelbyGT500]

Do you know where I can find the connector in the car?

 

[08TorchRedShelbyGT500]

06 4.0, coupe, automatic. My radiator fan refuses to turn on, and it's not a relay or fan motor problem. After hot-wiring the wiring, it all works fine, but I don't know what else could be causing the fan to not turn on. If anyone has any ideas please let me know.

Well, with all the info you received, have you fixed the issue?

 

[burnettdylan]

Well, with all the info you received, have you fixed the issue?

I took it to my buddies shop just to have him look at it, it turned out it was the wiring from the fuse box. The wiring was completely burnt through.

 

[08TorchRedShelbyGT500]

I took it to my buddies shop just to have him look at it, it turned out it was the wiring from the fuse box. The wiring was completely burnt through.

I see. And do you know why that wiring would actually burn up? Fixing the wiring in the fuse box will repair that part of the car, but knowing why that wiring burned up will happen again unless you fix the reason it happened, and that generally leads to a failing cooling fan assembly. Those wires don't melt themselves. That is caused by an engine component that is drawing too much current, which melts the wires over time. That item is the fan motor assembly. Unless you want that to happen again, I would get that engine cooling fan assembly checked and most likely REPLACED!.

 

[StockishS197]

This is

I see. And do you know why that wiring would actually burn up? Fixing the wiring in the fuse box will repair that part of the car, but knowing why that wiring burned up will happen again unless you fix the reason it happened, and that generally leads to a failing cooling fan assembly. Those wires don't melt themselves. That is caused by an engine component that is drawing too much current, which melts the wires over time. That item is the fan motor assembly. Unless you want that to happen again, I would get that engine cooling fan assembly checked and most likely REPLACED!.

This is unfortunately a very common issue with all S197s. The wiring and BEC is poorly designed and it’s easy to overload the wiring, connectors or fuses as the fan ages and pulls more amps. If you don’t catch it soon enough, it can burn through the wiring and BEC just like this.

There’s a few good write ups on ways to rewire the high and low speed fans onto a dedicated higher amp rated fuse block that would solve the issue.

 

[08TorchRedShelbyGT500]

This is

This is unfortunately a very common issue with all S197s. The wiring and BEC is poorly designed and it’s easy to overload the wiring, connectors or fuses as the fan ages and pulls more amps. If you don’t catch it soon enough, it can burn through the wiring and BEC just like this.

There’s a few good write ups on ways to rewire the high and low speed fans onto a dedicated higher amp rated fuse block that would solve the issue.

Yep. I had done some research on this issue. My car hadn't experienced this issue, but I decided to make sure I didn't, so I purchased the Dual Relay Fan Harness from WireEverything, and I also purchased a new Ford Performance SVT 7 Blade 2013-2014 Fan assembly for my car. This project was done in Feb 2026. The install went well, and now my new fan assembly bypasses the fuse/relay box entirely and runs the 8-gauge wire to the battery ground and is connected to the power input terminal entering the fuse/relay box. The update sure is a great piece of mind!!!





New fan assembly. This puts out 40% more air than the stock cooling fan, and it now runs on wires that can handle the current.


Power connection to the Strut Tower side of the Fuse Box with a new 8-gauge terminal from the Dual Relay Harness.


Dual Relay Harness Location I picked.


Harness Fuse and 8-gauge battery chassis ground location for the new harness.


The completed wiring harness is installed. You can't even tell I installed it. No more worries about melting or burning wires.


This wireeverything video explains the whole issue.

 

[brasil]

bought the HD wiring from wire everything. Perfect DEAL ! Couldn´t be happier

A MUST have for every S197 Mustang -in my opinion.