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Thread: Weird chirping noise (when heater is on)

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    Default Weird chirping noise (when heater is on)

    Okay, this has been happening for a while now. I drive a 99 sport 2wd. Usually, when I turn the heater on, the electric fan turns on and off every 10 seconds or so. Whenever the fan gets to its peak RPM, there is a weird deep chirping noise, like a belt is slipping up or something. I would like some input on this situation before I take it to a dealer. A friend of mine (who doesnt drive a jeep) said its my water pump bearings, and said I should replace the water pump. I don't know how he came to that conclusion, but whatever. I would go take a video of what I'm talking about, but its a little late right now. Any and all help is appreciated

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    did you check for baby chickens???:wavin2:

  3. #3

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    I would say the bearings in the blower motor,(squirrel cage)

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    What you're saying is that ONLY when the heater motor is on high it makes this noise? If the noise only occurs when the blower motor is on, then the blower motor is probably on it's way out as skooter-351 mentions. There is no belt involved with the blower motor...just an input voltage to the motor and step down for the different speeds through the resistor block.

    The good thing is that generally these motors aren't too tough to replace.
    Consult your Haynes, Chilton or FSM (best in my opinion) for more info....
    99 XJ Sport, 4.0, A.T. NP242 "Daily Driver"
    Past Jeeps: 49 Willys, 81 Scrambler, 88 Cherokee

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    didnt we just have this thread?
    http://www.jeepsunlimited.com/forums...d.php?t=875862
    cliff notes version: electric fan cycling = defrost = A/C pump = belt tension

    here's a question, have you had your serp belt replaced in the last few yrs?

    yeah, it COULD be water pump bearings.. but eliminate the easy stuff first. spray a bit of water on the belt and see if that chirp gets better/worse. (just DO NOT use belt dressing whatever you do.)

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    I have had the same exact chirping noise you describe,Change your blower motor,that's what fixed it for me,do it soon or you'll be replacing your blower fan
    switch wire connector(it gets so hot it melts in your dash)don't believe me, pull your heater controls and have a look,it'll burn out the resister's also,you will only get one fan speed,then it starts getting expensive.The motor shaft was so worn
    it started boring a hole in the motor housing.A new lifetime blower motor costs around 35.00 at advance auto near me.

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    also,i just cut off my melted fan blower connector,made a paper diagram what wires went to what switch terminals,and soldered all my connections,it was tight
    but can be done with patients and a good soldering iron.my new blower motor works great now.
    i have to fix the blower door now because of the deteriated weather stripping,wife says she can feel cold air as we are driving.

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    Wow! ^ That never happened to mine, it just gave up the ghost.

    If you really think it's the blower, jump the connector in the engine bay. While you're at it, run the engine with the heater on and see if it's the belt. Spray a little waer on it. A good sign if the water pump is the culprit is coolant leaking out of the weep hole.
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    Quote Originally Posted by sgtpepper View Post
    didnt we just have this thread?
    http://www.jeepsunlimited.com/forums...d.php?t=875862
    cliff notes version: electric fan cycling = defrost = A/C pump = belt tension

    here's a question, have you had your serp belt replaced in the last few yrs?

    yeah, it COULD be water pump bearings.. but eliminate the easy stuff first. spray a bit of water on the belt and see if that chirp gets better/worse. (just DO NOT use belt dressing whatever you do.)
    I just had it replaced yesterday, along with the water pump. Now the chirping is even worse, even at idle. I will have a video up soon of exactly what it is doing. I think the belt is too tight, I'll work on it later on tonight.

    *edit* Heres the video

    http://youtube.com/watch?v=YEHNw8Z4HbQ

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    Kaws,you say when you turn your heater on you hear the chirping noise,and then you say electric fan,heater blower fan or radiator cooling fan?The more you describe in detail,the more someone might be able to offer a solution.have a great day!

  11. #11

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    Okay, the video helps. This doesn't appear to be a heater blower motor problem. Sounds like the noise is coming from the FRONT of the engine bay.

    You said that you had the serpentine belt replaced yesterday and that it's still making the noise.......the belt has to be pretty tight so be sure the tension is correct. My 99 is really susceptible to belt noise and I have had to retighten each new belt after only a few minutes to eliminate the squealing.

    After watching/listening to the video, the noise starts immediately after you turn on the A.C. the video shows you turning your switch to an A.C position. The problem could be the A.C compressor/clutch. If it's quiet with A.C not on and noisy with A.C on, then logic tells you to concentrate on the A.C system.

    I would find a mechanics stethoscope and put that on the A.C. compressor when this noise is taking place. If a bearing is going out in there, it should be pretty easy to isolate.

    It could also be any other component or idler pulley along your serpentine route but yours does sound like an a.c. compressor starting to go south IMHO.

    Good luck and let us know what you find out....
    99 XJ Sport, 4.0, A.T. NP242 "Daily Driver"
    Past Jeeps: 49 Willys, 81 Scrambler, 88 Cherokee

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    Use a piece of heater hose(2 feet long or so), hold it to your ear then move the other end around the motor. Works as well as a stethoscope, and is something usually laying around.

    I cant tell but it doesnt sound like the same squeal I had.
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    If the electric engine fan is cycling when you turn the 'heat' on, the compressor is on. I'd suspect a loose serpentine belt. If that is kosher, then something else is putting drag on the belt, causing it to 'chirp'.

    I'd definitely make sure the belt is tight enough first before suspecting a compressor or bearing going out.
    94 XJ Country NP231 AW4, 145k miles
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    Quote Originally Posted by lakerXJ View Post
    Okay, the video helps. This doesn't appear to be a heater blower motor problem. Sounds like the noise is coming from the FRONT of the engine bay.

    You said that you had the serpentine belt replaced yesterday and that it's still making the noise.......the belt has to be pretty tight so be sure the tension is correct. My 99 is really susceptible to belt noise and I have had to retighten each new belt after only a few minutes to eliminate the squealing.

    After watching/listening to the video, the noise starts immediately after you turn on the A.C. the video shows you turning your switch to an A.C position. The problem could be the A.C compressor/clutch. If it's quiet with A.C not on and noisy with A.C on, then logic tells you to concentrate on the A.C system.

    I would find a mechanics stethoscope and put that on the A.C. compressor when this noise is taking place. If a bearing is going out in there, it should be pretty easy to isolate.

    It could also be any other component or idler pulley along your serpentine route but yours does sound like an a.c. compressor starting to go south IMHO.

    Good luck and let us know what you find out....
    I doubt it is the A.C compressor, as there was no squeal before the belt was changed. I'm pretty sure it has to do something with the belt tension, and the contact its making with the new water pump. I came to that conclusion when I noticed the pitch of the squeal changes slightly whenever that yellow section of the belt makes contact with the pulley. The question is now, should I loosen or tighten?

  15. #15

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    There is some confusion in troubleshooting this in that your first post you said this has been happening for a while now and then your last post you said there was no squeal before the belt was changed and the belt was just changed yesterday. I think some of us assumed that you had the squeal both before and after the new belt, that's why we're giving you other things to look at.

    IF this squeal started immediately after replacing the belt and water pump, then the problem is belt tension, almost assuredly. In most cases, it isn't tight enough. Be careful though as too tight isn't good either. If you get the belt really snug and it is still making noise, you could have a bad water pump out of the box too. Good luck....
    99 XJ Sport, 4.0, A.T. NP242 "Daily Driver"
    Past Jeeps: 49 Willys, 81 Scrambler, 88 Cherokee

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    your heater will not cause the AC compressor to cycle..maybe you have it on AC or defrost? my serpentine belt will squeak or chirp when it is damp outside or after a rain because it is a faulty, newer belt. it is plenty tight. do not over tighten the belt as that puts extra strain on all the pulleys. The belt is the cause, whether or not it is tight or it just may be a bad one. also, as said before, chech the blower motor, but it runs whether you have the heat, ac, or defrost on, so it should do it all the time.
    NCState

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