problem w/ radiator cooling fan

[kennyo]

my car seems to only overheat after extended driving in stop and go traffic(highway driving seems ok)and if i turn my a/c on it will start blowing hot/warm air and cause it to overheat.I brought it to ford and they told me to replace "high speed fan resistor",which i did and problem still persists.I checked voltage on fan harness for low speed and high speed and both work as advertised.My fan seems to turn at times and other times not(even when voltage should be going to it).My question:before i go and order this fan w/motor,does anybody know what this high speed fan resistor does and how to check it?The hanes manual doesn't even make reference to it.Thanx in advance

 

[ToplessStang]

What year is your car? Also I've heard of low speed resistors for engine cooling fans (limits current to fan motor) but never high speed resistor.

The Mustang (01-03) doesn't have a seperate engine cooling fan resistor so I have no clue what you changed .

 

[kennyo]

the car is an 03 mustang gt.Ford called it a high speed fan resistor,but when i bought the part,the guy looked at me strange and said it was a fan resistor.It is located on the top left of the fan cowling(looking from front of car back).Where the wiring harness hooks up to wiring harness of fan's motor.about an inch forward a wire(looks like the low speed wire)branches off to this resistor ,comes out of resistor and goes back to harness going to fan motor.Hope that helps.Thanx for the input

 

[ToplessStang]

the car is an 03 mustang gt.Ford called it a high speed fan resistor,but when i bought the part,the guy looked at me strange and said it was a fan resistor.It is located on the top left of the fan cowling(looking from front of car back).Where the wiring harness hooks up to wiring harness of fan's motor.about an inch forward a wire(looks like the low speed wire)branches off to this resistor ,comes out of resistor and goes back to harness going to fan motor.Hope that helps.Thanx for the input

Ok well I stand corrected . I was looking in the Ford wiring diagram and don't see it but after mentioning your car being an 03 I went down to the garage and yup, that's a low speed resistor.

That being said, if you have voltage comming out of that resistor with the A/C on and getting to the fan connector but the fan is not working it is the fan motor. Also make sure that the ground at the BLACK wire on that connector is good. An easy way check is to put one end of your test light to the POSITIVE side of the battery and your other end on the black wire. Should light up.

 

[kennyo]

still not sure how to check resistor.Its a 2 prong plug that hooks up to it and both wires are red.The only bare metal showing when hooked up is on the resistor side

 

[kennyo]

just so i understand the theory of its operation.The low speed is constant thru the resistor at a certain high temp and then more voltage comes out when in high speed?

 

[ToplessStang]

The way it works is that on low speed the current will flow through the resistor thus reducing the current and causing the fan motor to turn at a reduced speed. At higher temps the current will go through a diffrent wire with almost no resistace (high speed).

You should have 2 ORG/RD wires going into the resistor. That is where it comes in full power and comes out at a reduced amperage. If you look carefully there is another wire in the harness that is ORG/BLU. That is the High wire. Then of course you also have the BLK ground wire. If you have voltage going in to the resistor but not out that would be a problem with it or the terminals in the connector. If all is ok there, all that is left to check is at the motor. If voltage is good there, motor needs to be replaced (assuming the ground is good).

 

[kennyo]

the only thing i see with the 3 wire you are talking about is on the main wiring harness hookup to the fan.Where the resistor is:the wire going in is red and the wire coming out is red,no ground wire or red and blue wire,as on the wiring harness conection.I appreciate your input,by the way.I really dont wanna buy this fan/motor and it is something else.Do you have any idea where the motor could thbe bought seperately?most places ive looked incorporate the fan with the motor

 

[ToplessStang]

Where the resistor is:the wire going in is red and the wire coming out is red,no ground wire or red and blue wire,as on the wiring harness conection.

There are 3 wires that go to the motor. One of them takes a little "detour" if you will and goes into the resistor and comes out and goes to the motor. It is normal to have only two wires at the resistor.

Weather you can buy the motor by itself, no clue.