1995 Mustang Cobra Radiator Fan operating only when A/C is on AND only for a few seconds!

Alfadragon17

New Member
Jul 30, 2019
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Kansas City, MO
Alright, I am coming here after reading several forums and receiving no specific answer for my problem though a lot of useful answers to symptoms that my friends car shares with others. My friend has a 1995 Mustang Cobra that's been sitting for 6 years with no coolant in it. Without going into much detail about who or how he obtained the car (since I don't know) the car has had an overheating problem since he parked it; though not the main reason why (the differential fluid leaked out and seized the diff up).

To start off, We've have done what most others here (and on other forums) have suggested for a 5.0L 1994-2004 Mustangs: We've have changed the ECM temperate sensor and dash temperature sensor, verified that the radiator fan is operational in both high and low settings, he changed the thermostat before he parked it 6 years ago but we don't know if its stuck closed yet, we went to the junk yard and gambled on two used CCRMs which both work since the fan does come on briefly when first started (this is regardless of the car being hot or cold...), we know the coolant is not hot (above 160 degrees Farenheit) checked with a infrared temperature gun at the engine block where the thermostat is, we have checked the fuses associated with the radiator fan, CCRM etc... they were not blown or scorched, the fan connector was not scorched or melted, the CCRM connector was not scorched or melted.

Currently, the fan only spins up at start (briefly remember) when disconnected and, bypassed by jumping the two leads inside the connector together while the A/C is running full blast. Then it shuts off.

After reading through some forums here I am a little concerned that we may have not burped the engine properly and air exists at the top of the engine by the sensors. But even if that was true (which I believe it might be...) why would the fan not kick on when the A/C is on full blast with the new temperature sensor?

I also believe it could be an electrical problem with the alternator going out not providing enough power to system but, that I am not certain about since we have not load tested the alternator yet.

We will be testing the thermostat to see if it still operates. We will pressure flush (with a garden hose) the coolant system to try and remove any air bubbles.

We are at the point were we are considering just jumping the fan to the battery and unplugging it when its parked and off.

Has anyone else had this string of problems? More importantly, has anyone got a solution/insight to this compound issue? Any help is much appreciated. As people ask questions I will likely have more information that I might not remember at this moment...
 
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HISSIN50

"How long does it take to get help in here?
SN Certified Technician
Nov 29, 1999
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Your post is a little confusing.

Have you bench tested the fan motor? Disco' the pigtail to the fan and apply FUSED battery power (and ground) to the low speed and then the high speed fan terminal to ensure each speed spools up and stays running?

Is the ECT disconnected? The fan should not come on at startup.