So here's the deal: My Ranger's overheating. Sometimes. It's a 2002 2.3L XLT with about 172k miles on it. Symptoms include:

Overheating when AC is on. It takes a while to cool off, but once it does the truck starts to overheat.

Overheating in traffic or when it's above 80 degrees. Which in Portland isn't too often :P

Other than that the truck runs at normal temperature. I've replaced the thermostat ( and housing, it was all together), replaced the Engine Coolant Temperature Sensor, the Auxiliary Fan Relay, flushed and cleaned the radiator, tested the auxiliary fan with 12V and it runs fine.

What it's NOT doing: Pushing exhaust into the coolant, or coolant into the engine. I'm not losing coolant at all, so I doubt it would be a head gasket. I am able to control the temperature of the truck ( according to the gauge, which seems to be working fine) by turning on the heater. Also, my water pump and fan clutch are working properly. I do have another question about my AC and it's ****-shiver, but that'll be another thread :P

My guess is that it's something to do with the Auxiliary electric fan, which is not turning on at all. I used to be able to hear it, even after the truck was turned off it would run for a bit. Is there some other kind of connection that I should look for? Is it a computer issue? Or should I just put a switch in the cab to turn it on the way Jeep guys do it?

Thanks guys in advance, this is kinda bugging me!

 

If the aux fan isn't working, I would first check the fuses and relays. The aux fan is supposed to be triggered when the AC compressor is running, and I think it can also be triggered if the temperature gets high enough. Since you confirmed the fan will run if it gets power, it is safe to assume that for whatever reason it is not getting power during normal operation. I would start by trying to find out at what point the components that control the fan are not working. Is the relay getting 12V power? Does the computer or AC system trigger the relay on. If the relay is coming on, is it passing on power on the switched circuit?

 

Fuses and relays are working fine, and I can't very well trace the wiring from the fan because it disappears into the wiring bundle shortly after the connector. Could there be any issue with the computer involved? Perhaps the brain isn't telling the fan to turn on?

 

You may also want to check your fan clutch on the main fan (one bolted to water pump). The clutch may be worn out and not engaging at proper temp.

 

I am leaning towards 03 Maz reply on this myself. How did you check the clutch fan to make sure it is okay? Have you cranked the truck up, turned on the AC and verified that the electric fan comes on? I believe a standard clutch fan only engages up to %70. Very possible at the age of your truck the clutch fan is slipping too much. Reason I think this is the three years I have had my 06 2.3L Ranger I have never heard the electric fan running unless the AC was on. So if the computer told the electric fan to run for temperature control under normal circumstances I would think the clutch fan is failing.

 

I had thought the fan clutch too, but it has no problem running when the engine is warm. It's the electric fan that won't turn on at all, not even when the AC is on.

 

Looks like it would throw a code if the fan works when jumped out and the relay is good. I do think the computer tells the fan to come on also when a very high engine temp has been indicated or the AC compressor is on. I would think that a computer fault would effect more than one component though and should light up the check engine light. If the fan relay is good and getting power that same power runs straight to the fan. Have you checked to see if power comes to the relay when the AC is on? I bought the Ford Ranger 2006 wiring diagram book but don't have a clue as to what may be different for you with a 2002. You do have low pressure and high pressure switches that will shut the compressor down if they trip which should keep the fan off. If all this checks out I would have to wonder if it wasn't a computer glitch of some sorts. A switch could be easy enough to wire in if all else fails.

 

I am having the exact same problem/symptons with my 02 duratec 2.3. When the outside temperature is below 80 degrees, I have no problems at all, evening blasting max A/C for 60 miles. I also have replaced all the things you mentioned with nothing helping my issue. I can't tell if the electric fan is running or not when the car is on, due to mechanical fan spinning in my view. I know the electric fan works, because I hooked up a 12v to it.

Today, I just bought a new fan clutch and water pump, but before I install, I wanted to see if the internet could help. I would imagine that the fan clutch wouldn't be the issue, as I have a friend, (two streets over from me, with the same motor) who completely took out his mechanical fan and relies strictly on the stock electric fan, wired to run all the time. He has had it that way for 6 years and has never had an overheating issue.

Running out of ideas, but the diesel in my 550 is attacking my wallet.

1965hhorunner--- did you find a solution?

Thanks for any info.

 

Unfortunately I was not able to find the real root cause of the problem, but I did manage something that works. Much like your buddy, I simply hard wired the electric fan, but I kept the fan clutch engaged. I ran direct off the battery to a switch in the cab. So basically the only 3 things in the circuit are the battery, the switch, and the fan. Biggest problem is forgetting to turn off the switch at night and running my battery dead I'd like to know what your buddy tied into, just so I wouldn't have to worry about it.

 

He did the same thing as you... just hooked it to a switch in the cab.

 

Yesterday, I replaced my water pump, fan clutch and put another new thermostat in... problem solved, after 314 miles of driving over some mountains to the desert and back with the A/C on the entire time, not once did the gauge go over the midway.

My fan clutch definitely needed to be replaced. I could stop my old one with my finger... now I have chunk of skin missing off my finger after testing the new one.

My water pump seemed fine, but I replaced it regardless, because it was only $30.

My thermostat was okay as far as I could tell by looking at it, but I put a new one in anyhow and returned the one I bought last week.

I don't know the exact cause of the issue, nor do I know the exact solution... I would doubt the fan clutch would make that big of a difference considering the fact that there is an electric fan too, but my problem went away.

 

On the 16v duratec engines there is a sensor on the back of the head that tells the ecm what the head temp is. If it is bad it can cause the fan to not come on when needed. Oh and you have to pull the tranny to change it.