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Discussion Starter · #1 ·
My mustang seems to not be cooled properly while i am idling. If i sit in my car and let it idle for about ten minutes the antifreeze starts to boil and come up through the cap. At first i thoungt it was just a bad cap so i replaced it. The problem has continued so i started looking around and now i am thinking that i need to replace the temperature sensor that turns my fan on and off. I was also wondering if anyone knows if the fan on my model has a hi and low speed? When i am idling with my a/c on i can hear the fan kick on about every thirty seconds and then it kicks off and i was wondering if it should be going to a higher speed if it has one? Also something else the might help is that when i idle the a/c will cycle from cold to somewhat warm and then work its way back to getting colder. I just thought that my fre-on was low so i hooked up a tester to my a/c line and when the fan is off the a/c blows cold air but the tester reads that i am low on fluid. When the fan kicks on the tester reads the i have the proper amount of fluid in my a/c but then it blows out warm air inside. I hope that i just need to replace the cooling fan temperature sensor to solve both problems but i have no idea if that is even the problem. I would really appreciate suggestions that anyone might have to solve these problems I'm having. Thanks
 

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Does it overheat with the AC on? How about off?
Have you checked your smart junction box for water damage?
(It was a problem in 2005's)
 

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Bad Thermostat??
 

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What does your temperature gauge say in the car when it overheats? If it shows the car as hot then it's not likely to be a sensor. Here’s a link to the engine fan wiring diagram. The PCM controls the fan, and it is two speed. My guess is a bad thermostat too.

Ford Service Manuals - Wiring Diagrams
 

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Discussion Starter · #7 ·
Yes that was another problem i forgot to mention is that the temperature gauge inside my car will be right where it normally is even when the antifreeze is boiling out. And i think i've narrowed down my problem to the fan sensor or the thermostat but my understanding is that a thermostat will either work or it wont but i could be wrong im not sure about that. Thanks.
 

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If the coolant is boiling but the temperature gauge reads normal then there’s either a faulty temperature sensor, or the system isn’t holding pressure for some reason (a loss of pressurization will allow the coolant to boil at normal engine temperatures). Have you tried squeezing a radiator hose while it’s hot to confirm that the system holds pressure? Maybe the new cap’s a piece of junk?? (wouldn’t be the first time)
 

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Discussion Starter · #9 ·
Ha ha yeah you are right about the caps. But yes the hoses have good pressure in them. I think im going to replace the cooling fan control and see if that will hopefully fix my problem. And thanks for helpin me out everyone.
 
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