03 Gt Cooling Fan Issues

Discussion in 'SN95 4.6L Mustang Tech' started by Scal0704, Jun 15, 2014.

  1. My 03 GT has been having overheating issues for quite some time. The cooling fan will not run when the car gets hot, but will run if I turn on the A/C.
    Yet, even if I run the A/C, the car overheats after about 10 minutes of city driving. When I turn the A/C on and turn the temperature dial to hot, that prevents overheating. But since I live in Florida, I need the car to run efficiently with the A/C blowing cold air. I've never had issues with the A/C producing cold air.
    The temperature gauge works until it reaches halfway then does not continue to move past that point, even though I know the engine is much hotter.
    I went to a local Ford dealership for a diagnostic test, where I was told I needed to replace the cooling fan assembly and that my battery was weak (perhaps this overall cooling issue is causing wear and tear on the battery?).
    The cooling fan and thermostat were both replaced about 2 years ago when the car was overheating. The issue back then was a plug in that is located by the fan towards the passenger side (my dad is my mechanic, so I apologize for not knowing exactly what this plug in part is...).
    I went to purchase a new cooling fan assembly from AutoZone, where the employee there talked me out of that and into buying a new temperature control sensor based on what I told him. I already replaced the CCRM thinking that was the issue before I brought it in for a diagnostic test. I disagree with the diagnostic test because in my understanding, the cooling fan itself works however the fan isn't receiving the signal to activate when the engine is hot. So to me that would mean it would be some sort of sensor or relay that is bad, but I very well could be wrong. But right or wrong, it just want it fixed!!
    Any advice would be GREATLY appreciated!
  2. The high a low speed relays are in the CCRM. If the fan is running then it should be OK. You can try jumping it with a direct connection from the battery to make sure. If I'm not mistaken the temperature control sensor is the one mounted to the intake manifold? Did you replace it? That is what sends a signal to the PCM and in turn signals the fan thru the relays to activate the fan. The high speed fan will only come on when the car is hot AND the AC is on.

    To test the fan relays, start the car. When it reaches operating temperature (high side of normal) the low speed fan relay should kick the fan on. You can probe the connector to see if it is getting voltage from the relays. Do you have a volt/ohm meter?