Okay so about a week ago I noticed that my air conditioner wouldn't blow cold anymore when I was sitting still..

Today the most random thing happened. I was driving and looked down and saw my engine temp was all the way in the red. I immediately pulled over. Looked for leaks and nothing. Slowly opened my coolant tank and it was starting to spew. So I don't believe my coolant is low. I was looking everywhere for the fan and couldn't find it. Yes I know probably a rookie movie but at least I'm admitting it.

I will end up taking it to a shop to get looked at but I would like to diagnose it before I go so they don't spend forever trying to fix the problem and cost me tons of money.

After I let it cool off it did good on the 10 mile drive back to base but as I was pulling in the parking lot I let it sit again and it rose right back up into the red.

 

By the way this is a 2007 Mustang GT. With 31,000 miles.

 

Alright so after my car cooled down a bit I went back out to look over things. Started it up and found my fan and noticed it wasn't spinning. What could be causing this? I believe this is the problem.

 

does it run when fully warmed up? could be a faulty fan module. i put a aftermarket oil and temp gauges to moniter. factory gauges are really glorified idiot lights. i can watch my temp gauge and tell when thermostat opens and oil pressure readouts from idle to cruising. factory oil pressure is either on or off, does not flucuate.

 

My 05 GT did almost the same thing yesterday too there was not smoke or any coolant smell or any leaks and my fan was working. I let mine cool all the way down then turn the ignition key on and the temp gauge needle stop in the middle indicating the car was warmed up when It was a cold start up so the needle should have been all the way far left. Someone pointed out to me that it could be the step motors that move the needle on the gauge cluster is faulty which from reading a lot of complaints on the gauges seem to be a very commen issue.

 

Well my car honestly didn't seem like it was overheating. Although it was running funny when the temp gauge got in the red.

It only gets hot when I'm idling or driving really slow. Which lead me to believe it is my fan. I let it sit and get hot yesterday again and still noticed my fan wasn't kicking on.

So today I'm gonna bite the bullet and let carmax do warranty work on it for 250 dollars.

 

The coolant fan should run whenever the A/C is turned on, regardless of the coolant temperature.
If the fan doesn't run with the A/C on, then one(or more) of the following is bad: fan motor, high speed engine cooling fan relay, high speed fan component in the electrical connector on the fan shroud(or may be loose), high speed fan wire/connection somewhere else in the high speed fan circuit(or may be loose), high speed fuse box component, high speed PCM component, loose/corroded fan motor ground connection, or bad fan motor ground wire.