I have a 2002 Dodge Ram 1500 two wheel drive with a 4.7 liter engine.

It's been overheating so I replaced the whole cooling system:

  • I replaced the condenser cooling fan because its not coming on when the trucks getting hot. It comes on when I turn the AC on.
  • I replaced the relays, also still not working
  • I am getting no fault codes, no check engine light

The only other thing I think it could be is the computer.

  • 1
    Could you add more specific information on what was replaced in the cooling system. The AC fan has nothing to do if the truck is overheating.
    – vini_i
    Commented Sep 3, 2015 at 11:09
  • 1
    Did you replace water pump, do a hot flush, did you replace the radiator cap? Is the system full of coolant? Is the coolant 50/50 or all antifreeze? Commented Sep 3, 2015 at 18:48
  • 1
    I'm going to ask the stupid question here: Did you change the thermostat? Commented Sep 3, 2015 at 23:42
  • Here are the things that I replaced I replace the water pump the thermostat the coolant temperature sensor the belt the fan clutch. I checked all fuses and I replaced the relay switch for the condenser fan and by the way it does help cool your car because when your car starts getting hot that fan comes on to help cool it and also comes on when you turn the AC on
    – dennis
    Commented Sep 4, 2015 at 15:40
  • 1
    I wouldn't be surprised if that was the intended logic of that fan. The fan turns on when you turn on the AC, so that verifies the wiring, fuse, and relay are good. Does it overheat stopped at idle, moving down the road, both?
    – rpmerf
    Commented Sep 4, 2015 at 17:03

4 Answers 4


I believe that fan has a two speed motor, three leads on it. One is low speed operation which is turned on by the AC system. The second is the warm engine connection which is high speed fan. This is controlled via a temperature switch through a relay.
With this knowledge need to test and or replaced the temperature sensor and the relay that is this high speed part of the fan. Or if you have a volt meter then measure the fan connection for this high speed circuit looking for it to turn on and off with rising heat.
The circuit is pretty much the temp sensor, relay, fuse, and fan (plus wiring).


It is not an answer exactly but I can't comment yet...sorry for that...

It might sound weird but sometimes wrong cam timing can cause overheating of a motor because the combustion is not as efficient as it should. A lot of the heat is trapped inside the chamber and not exiting the cylinder properly. Since you replace the whole cooling system that is the most logical explanation.

Finally make sure that nothing is blocking the airflow to the radiator. The most obvious is in front of the bumper but don't forget the section between the bumper and the radiator.

  • 1
    I think wrong cam timing (on non-adjustable cams) would create a lot more symptoms than overheating. Still, this fully qualifies as an answer, not a comment. Thanks for you participation.
    – SteveRacer
    Commented Sep 3, 2016 at 4:50

Try burping the system. My 02 dodge did same thing and I replaced water pump, thermostat, fan clutch, radiator, and even flush the system. Some reason heater core sits higher than reservoir so you have to Jack front end up on ramps and then burp the system. Once I did this no more running hot.


When the vehicle is cold pull the radiator cap off making sure that the radiator is full of antifreeze start the vehicle up now if you see bubbles coming up from the antifreeze almost at a regular pace it may be a blown head gasket

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