Overheating - fan only works with AC on.

[Dan04COBRA]

Diagnosing an overheating issue. So far confirmed intercooler pump works and fan works with AC on. However it still overheats with AC on.

Someone suggested i test continuity for the resistor switch found under the intercooler resevoir. Its reading .3ohms only. The spec I seem to find is either 3.3 or 7.

To confirm water pump and thermostat is okay, can I start the car with the radiator cap off and look for flow?

 

[Dan04COBRA]

Just ran the car up to 198 in the driveway. Radiator freezing cold, didnt see coolant level fluctuate at all. Fans never kicked on either.

 

[wckdvnm]

Just ran the car up to 198 in the driveway. Radiator freezing cold, didnt see coolant level fluctuate at all. Fans never kicked on either.

That’s the sign of a bad thermostat. You need to remove the fill plug on the crossover tube. The won’t be movement in the tank from all I’ve seen.
Pep boys sells the stant 180 thermostat which has a wide opening like the riesche one. It is what I use. Best to clean your radiator out while it’s out. The company that made the cheap 3 row rads sold out quick.

 

[wckdvnm]

Just ran the car up to 198 in the driveway. Radiator freezing cold, didnt see coolant level fluctuate at all. Fans never kicked on either.

Also is the car tuned or completely stock?

 

[Dan04COBRA]

Car is tuned. This hasn't been an issue for the first 2 years I've owned it. Has a 170tstat from previous owner.

Biggest concern is no fans. I figured it may be airlocked.

 

[Dan04COBRA]

Should clarify from original post - fan does not run at all unless AC is on.

 

[01yellercobra]

Is the crossover getting hot? If the temp sensor isn't seeing enough heat it won't turn the fans on. You said the coolant is still cold. Sounds like a flow problem to me.

 

[Dan04COBRA]

I never thought to grab the crossover. The top hose gets hot as hell.

 

[MalcolmV8]

Had you done any work on the car leading up the problem? Possibly air locked. A lot of people have trouble burping the cooling system on these cars.

If not then your water pump or thermostat has likely given out on you.

 

[hotcobra03]

I've had this..

connector..fan side..barrel was pushed back..

 

[procharger]

Ohm engine coolant sensor or while at idle remove connector from sensor and the fans should kick on, if not your sensor is INOP.

Sent from my [device_name] using the svtperformance.com mobile app

 

[2003SLVRSNAKE]

Dan04COBRA, Did you ever figured out what the problem was?

 

[cdnstang]

I have a weird anomaly with one of my cobras that i have had remote tuned. The fans would not kick on unless in the defrost position. I tested everything from sensors, to ccrm and replaced relays. What we found was i had to have the remote tuner make sure he left the fan settings unlocked and i would have to set the temps for the fans with my hand held and everything worked great then.