The radiator fan on my '03 Cobra doesn't come on during normal driving, and I'm trying to figure out why.
History:
I bought the Cobra in 2020 from a seller in Texas. I flew down and when he picked me up at the airport in it, it overheated. We discovered that the radiator fan physically would not spin; one of the blades had cracked and wedged itself against the housing. He bought a new assembly, we installed it, the car checked out fine after, and I drove it 800 miles home.
A year ago or so, I started noticing the radiator fan occasionally not working. As in the coolant temp would creep up over 200 under normal driving conditions (fan is set to come on around 185 or 190), but it would usually recover and overheating wasn't an issue.
The issue got worse, to the point that the radiator fan no longer kicks on at all during normal driving. If stuck in low-speed traffic, the coolant would get to 220F or more, so I stopped driving the car except for trips where I knew there would be minimal traffic and when it was cool outside. I figured it was the fan resistor so I installed this: "Radiator Resistor 1R3Z-8L603-AA Fit for Ford Mustang 4.6L V8 2001-2004" from Amazon--for some reason I can't post a directly link.
No change. So as a test, I flashed the ECM because I know that when the flash is being applied, the radiator fan kicks up to full speed. The fan did come on, but it sounded like it was only at low speed.
So then I jumpered the fan directly to the battery, and both the low speed and high speed circuits worked properly, so the fan itself is presumably fine.
More Googling suggested that the CCRM could be bad. In addition to the radiator fan, the CCRM controls the AC (it worked fine when I started driving home from Texas when I first bought the car, but by the time I got home, it had gotten where the air coming out was barely cool; I haven't diagnosed the issue, since the car is a convertible and I pretty much never need the AC), and it also controls the fuel pumps (the car drives great 99% of the time, but occasionally when doing a pull, it'll completely cut out for a split second--I figured it was a fuel pump issue and this was on my to-investigate list).
I ordered a CCRM from Late Model Resto https://lmr.com/item/LRS-37517/mustang-ccrm-relay-pcm-fuel-pump-fan-01-04-4-6 but figured I would post about the issue here to see what I should check next, if the CCRM doesn't fix the radiator fan. Thanks in advance for any input!
History:
I bought the Cobra in 2020 from a seller in Texas. I flew down and when he picked me up at the airport in it, it overheated. We discovered that the radiator fan physically would not spin; one of the blades had cracked and wedged itself against the housing. He bought a new assembly, we installed it, the car checked out fine after, and I drove it 800 miles home.
A year ago or so, I started noticing the radiator fan occasionally not working. As in the coolant temp would creep up over 200 under normal driving conditions (fan is set to come on around 185 or 190), but it would usually recover and overheating wasn't an issue.
The issue got worse, to the point that the radiator fan no longer kicks on at all during normal driving. If stuck in low-speed traffic, the coolant would get to 220F or more, so I stopped driving the car except for trips where I knew there would be minimal traffic and when it was cool outside. I figured it was the fan resistor so I installed this: "Radiator Resistor 1R3Z-8L603-AA Fit for Ford Mustang 4.6L V8 2001-2004" from Amazon--for some reason I can't post a directly link.
No change. So as a test, I flashed the ECM because I know that when the flash is being applied, the radiator fan kicks up to full speed. The fan did come on, but it sounded like it was only at low speed.
So then I jumpered the fan directly to the battery, and both the low speed and high speed circuits worked properly, so the fan itself is presumably fine.
More Googling suggested that the CCRM could be bad. In addition to the radiator fan, the CCRM controls the AC (it worked fine when I started driving home from Texas when I first bought the car, but by the time I got home, it had gotten where the air coming out was barely cool; I haven't diagnosed the issue, since the car is a convertible and I pretty much never need the AC), and it also controls the fuel pumps (the car drives great 99% of the time, but occasionally when doing a pull, it'll completely cut out for a split second--I figured it was a fuel pump issue and this was on my to-investigate list).
I ordered a CCRM from Late Model Resto https://lmr.com/item/LRS-37517/mustang-ccrm-relay-pcm-fuel-pump-fan-01-04-4-6 but figured I would post about the issue here to see what I should check next, if the CCRM doesn't fix the radiator fan. Thanks in advance for any input!
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