I have a friend that just put a used 02 GT engine in his 00 GT. He asked me this question, but I never pay attention when i am driving. Does the engine fan normally come on during normal driving, without the a/c on? After the swap, his never came on, so he put a manual switch to turn it on and off. Is this needed? Thanks in advance!

 

Yes it will come on when your not doing much moving. Like in traffic. While cruising with little stop and go, it may not come on at all.

 

The fan on my 96 GT has 2 speeds.

I don't know about the newer Mustangs.

I have the fan configured to come on at 182F and kick into high-speed at 202F. (normal is like 200F and 220F)

I have a 180F thermostat to match that setting.

The fan comes on and goes off frequently. I'm glad I don't have to think about turning it on as I drive.

I also live in a hot climate though.

It sounds like your friend forgot to reconnect a coolant temp sensor or something.

I was thinking of rigging up a 2 color LED to the fan so I could see what it was doing from the pilots bucket.

 

Mine on my 04 GT does not come on unless I am stopped for a few minutes, excluding the a/c being on.

Have your friend do this ( http://mustangworld.com/ourpics/fcar/dtcodes.htm ) and leave it on degC and see when the fan turns on and off... it's measured in centigrade... if it starts pushing 110 and the fan doesn't automatically come on he will need to use the switch.

 

He plugged his SCT tuner up to it and there were no codes.

Sounds possible, but if he forgot to do that, wouldn't it spit out some type of temp code?