engine cooling fan won't come on (1995 mustang)

Discussion in 'SN95 V6 Mustang Tech' started by TORRES112, Mar 15, 2007.

  1. I have a 1995 mustang.

    Car over heated the first time....water pump was leaking.. replaced it. Car overheated again about a weak later... the hose from the water pump had a large tear, replaced it. Both times car overheated coolant spewed out everywhere
    (did replace coolant) .

    Then car would over heat when idle or driving at low speeds only. Discovered the engine cooling fan is not coming on.

    I replaced the engine cooling fan motor..still not working

    I replaced the coolant temp. sensor...still not working.

    found out the engine cooling fan on my car was recalled, took it to the dealership, they added a circuit breaker at connection..but said that wasn't the problem...they ran diagnostic test..test said the problem was the temperature sending unit..

    I replaced the temp. sending unit and the fan STILL won't come on:shrug: .

    So I'm guessing it's the wires or connection, should I assume it's the wires to the temp sending unit since that's what the diganostic test said was the problem?

    Any suggestions would be really appreciated.
  2. sorry the sending unit is only for guage display and has nothing to do with turning the fan on..the coolant temp sensor sends a signal to the ecm to turn the fan on..
    remove the plug from the sensor and jumper it with a cotter pin , key on ,doesnt have to be running. fan should turn on... see if it does and post back before i say more.
  3. I have a similar problem on my 99. Fan hasn't worked as far as I know for the 4 years i have owned it. Last summer I finally re-did the positive wire conection. I tested the wire along the way and it losses power somwhere in the wiring harness(no idea where). So i just spliced into it at the fuse box and wired a toggle switch into the car to mannually turn it on on hot days or when the engine temp gets too high.
  4. thanks

    thanks for responding to my message. I took it this afternoon to a repair shop, so far they have tested the fan, and confirmed that the fan will turn on, they say they have been running test ands haven't found the source of the problem yet...say to check back tomorrow.
  5. Make them chech your compression and check your oil.
  6. the fan is controlled by a relay right? what about jumping the relay? could be a possible relay problem?
  7. the fan is controlled through the ecm which sends power to the relay to turn the fan on. the ecm takes the signal from the coolant temp sensor to know what temp the fan needs to come on at.
    by jumping the plug to the c.t.s. with a cotter pin, basically tells the ecm
    its at full temperature.......if it will not turn the fan on, use a test light at the plug to the fan to see if it is getting power...if it is it would be between the plug and
    the fan, if not you have to work backwards and check fan, relay, ecm, cts,...
    the most common problem ford had was the plug connection to the fan itself.
    that is why they recalled, for a fan resistor install between the plug to the fan and harness..why? because the fan plug was melting, overheating, causing the three wires encased in the fan plug to melt the plastic that seperates the 3 wires.
    causing the ground wire and the power wire to touch.. result ..fan inoperative..
    it is highly misdiagnosed because you cant see the melted parts of the plastic until you actually unclip the plug and look into it.
    i have replaced quite a few fan assy.. since they started having this problem in
  8. update

    they tested the fan, and said it works, it's capable of coming on....then they said it was the ccrm, said they would replace it for $386.00 , told them to go ahead...well today they replaced it and said that the fan still doesn't come on...it wasn't the problem, they put the old one back and are not going to charge.

    He said he thinks it could be the ecm, but does not suggest we replace it yet (same thing could happen, we replace it and it turns out not to be the problem). Say need to do test on ecm and wiring, costs about 79.00 hr/ min. of 3 hrs. this worries me, because I will pay a min. of $240.00 then who knows how much it would cost to repair the problem. not sure if i should tell them to go ahead with testing???

    says another option is to get ac fixed, if ac worked fan would turn on, ac has major leak, and possibly compressor needs to replaced, can run between $800-1100.

    asked about installing manual switch, owner did not want to do because, say fan motor will burn out faster, and did not want to be responsible for future problems.

    I live in texas, weather has been nice, but soon it will be very hot, avg. day 95-100+ temp, and we will need to cooling fan to come on more frequently than now.

    when replaced the fan, connection looked ok, and I took it to ford for recall and they installed a part between fan and connection, but could be wires

    should i maybe take it to somewhere where they specialize in electrical problems only? ....maybe they would be more familiar with this problem.:shrug:

    thank you everyone for responding any more suggestions are GREATLY appreciated.
  9. hhhmmm thats a tough one to answer whether or not he is good enough to diagnose it or whether he says he put 3 hrs into it only to tell you it needs a computer (e.c.m.) only because he couldnt figure it out in the first place..
    i couldnt judge that part for you..
    as far as the diagnosis if you are at all capable in basic electronics ( like how a relay works) i would say there are plenty of people who have converted to a manual switch, or even an aftermarket fan assy that could walk you through an install...
    even if you dont have the resources in diagnostics... for the price he wants to charge you for diagnostics and whatever parts and labor is needed to install.
    your better off visiting a performance shop in your area and have them install
    an aftermarket fan assy with automatic turn on, temp controlled switch/sensor.
    it may cost you 300 for the set up and to have it installed but you wont have cooling fan issues anymore...
    so my answer is do not have the diagnostic work done..pull the car out and pay the labor rate so far.. visit your local speed shop and go aftermarket..
    it will just cost to much for factory components and diagnostics...
  10. I would have to agree with above, I wouldn't have them do any more testing on it. I would say your best two possibilities would be to go ahead and do the aftermarket thing like 2muchtime says or go with just a manual switch. When i did the manual switch it took me maybe 15 mins to install, super easy. I'm not sure on the fan burning out earlier, maybe that is just due to you would keep it on while idling or short trips around town most of the time instead of a computer kicking it out after a certain temp was reached, but fans are fairly cheap to replace as far as I know and thats the route I went last summer, with just a manual switch.

    Best of luck in fixing the problem.
  11. If you turn the AC on the fan should turn on right away.
  13. Fuse? Short?
  14. another update

    I had heard from a couple of people if u turn on the ac, the fan will turn on....my ac doesn't work...blows hot air....but I thought it wouldn't hurt to try.....I was driving on hwy so temp was fine, when I was almost to my destination, there was one traffic light ....car started to go slightly above the R in Normal on gauge, turned on ac..and fan did not come one.....tried again when I got into the parking lot and temp started to go up again...fan didn't kick in. this was right before I took my car to this last repair shop.

    ok, so I went and picked up my car....they we're really nice..since they were not able to fix the problem, they were not going to charge me anything, not even for the tests..which I thought was awesome....said they kept thinking they figured out the problem..but everything they tried just didn't work.....they even tried putting freeon to see if they could get ac going and fan on.....said I had a major leak, all the freeon leaked out within hours and fan didn't come one....they recommened a shop that specializes in electrical problems.

    after I got the car home.... I took a look under the hood...the wires that went to my cool. temp. sensor used to be all loose and worn looking...and I had suspected that that could be the problem...they had replaced them...fixed my loose battery connection...and a couple of other things....so they had replaced or repaired things as they were testing and trouble shooting.

    I went on autozone.com, and looked up engine cooling fan...and the parts that go along with it , and I found a cooling fan motor relay: http://www.autozone.com/servlet/UiB...EGULAR+PARTS+LOOK+UP|~Cooling+Fan+Motor+Relay
    only 4.99, thought it wouldn't hurt to try to replace and see what happens...wasn't sure where it goes...assumed in the black box under hood, that contains fuses, and 2 relays...replaced one first...turned on car..while sitting in car noticed reciept said, ac control relay...which made me think to try again turning on the ac....turned it on and fan turned on immedietly:nice: ......... we wanted to make sure it was the new relay that had done it.....so we put the old one back on...... and turned the ac on again..and the fan came on immedietly again..so, it wasn't the new relay :shrug: . I'm thrilled that I was able to get the fan on at all, but i'm not sure what changed, it must've been something they did at the repair shop.

    right after I saw the fan come on with the ac, with new relay in, I turned off the ac, and let the car warm up...and temp still goes too hot, fan won't kick in by itself.

    talked to someone else who works at a shop and has worked on alot of mustangs... when he heard my problem he said it was a relay that goes bad and needs to be replaced......

    forgive my ignorance, but what is a relay....and where are they...is what he is talking about different than what I replaced today?

    again any advice is GREATLY appreciated.
  15. wrong location

    ok so I was definetly putting the fan control relay in the wrong place....I found a diagram online...the 2 I found in the black box with the fuses..one is for the starter, the other is for the horn......I was way off... where is the fan control relay located?
  16. yes it is possible it could be the relay.. i explained how to check it in my previous post... i will tell you again...
    this test is to see if the relay is working...
    remove the wires to the coolant temp sensor get a paper clip, open it, use each end, look inside the plug there are two wire ends (terminal ends) stick one side of the (metal) paper clip into one terminal and the other side of the clip into the other. so that you have made a half moon into the paper clip...and each end is sticking into the plug.

    go into the car and turn the ignition forward.. you do not have to start the car.
    it should start blowing... does it ??
    there is a coolant temp sensor and a coolant temp sendor about in the same location as each other if you are having trouble finding the right one,
    pull off each plug induvidually and watch the temp guage... if you remove the one for just the temp guage, the needle will move when its unplugged.. that is not the plug you want.. ifyou take a pic of the surrounding area i will point it out to you..
    if you can do a little diagnosing i can help from where im sitting ..
  17. Following up where 2muchtime is headed...

    I would suggest buying a Multimeter. You'll be able to test all of your electrical stuff to make sure things fall within operating parameters. Chilton's guide does a pretty good job of giving Voltage and resistance values. It saves a ton of guess work when try to figure out what's wrong with your car.
  18. I disconnected the wires to the coolant temp sensor and inserted the wire (paper clip), with key on or car on the fan turned on immedietly.

    Later I took out the metal wire , but still kept wires to coolant temp sensor unplugged, and fan still will turn on immedietly key on or car on.

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  19. you need a coolant temp sensor my friend..
    the reason for the paperclip is that you are actually telling the computer the car is
    running at 300 degrees..it is obviously NOT the computer otherwise it wouldnt have turned on.. trust me c.t.s is your problem..
    dont get it from autozone, for 2 more dollars get one from napa..
    everything should work properly after its installed..