High pitched whine

[A-TJ-J.D.]

Perhaps someone can help me ID a problem with my 04 TJ. For several years my fan controller for the heat and air was stripped out or would not engage. I had a shop fix it with a "junk" part. Afterwards, the fan speeds would engage and I thought it was fixed.. However, after a time a high pitched whine began to emit from the Jeep, this only happens when the heat is engaged and Jeep has heated up.If I accelerate, the whine stops, but when I'm coasting it comes back. A few months ago, my heater hose blew and they were replaced. After that, the noise went away. But it came back in about a week, as it did the last time, the noise is getting steadily louder. If I turn off the heat or air, and turn the fan speed down it stops. This is driving me crazy, and the noise is of a particular headache inducing frequency. Anyone know what's up?


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[JWjeepSask]

Mine does this but it's the opposite when I accelerate it has high pitched whine and when I let off the gas it stops. The harder I accelerate the louder mine gets as well. I self diagnosed mine as the stereo cause that's where the sound comes from. Also mine only has this strange phenomenon in winter...


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[A-TJ-J.D.]

Hmmm, that's a good thought, I think I'll pull the fuse on the stereo and see, but I'm pretty sure this is some type of pressure release or bearing problem, the sound seems to emit from the driver's side under dash area, and at it's worse, can be heard from outside the jeep. I just can't pinpoint the location. Also, like you pointed out, this is the opposite, goes off on acceleration.


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[Kevin Johnston]

My 03 has a vacuum whistle when the air temp is around 35°F or less. It will only whistle about ¼ throttle or less and only until it gets up to operating temp. I've got to where I can make it sound like the harmonica of Black Sabbath The Wizard.

I'm pretty certain mine is caused by the intake not heating up the same as the head making the gasket leak until the temps equalize.

Yours could be a vacuum hose or fitting on the HVAC in the dash.

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[bobthetj03]

My 03 has a vacuum whistle when the air temp is around 35°F or less. It will only whistle about ¼ throttle or less and only until it gets up to operating temp. I've got to where I can make it sound like the harmonica of Black Sabbath The Wizard.

I'm pretty certain mine is caused by the intake not heating up the same as the head making the gasket leak until the temps equalize.

Yours could be a vacuum hose or fitting on the HVAC in the dash.

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Off topic, but your avatar reminds me of a movie back in the day. "Hello Dave."

 

[Kevin Johnston]

Off topic, but your avatar reminds me of a movie back in the day. "Hello Dave."

Just what do you think you're doing, Dave?


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[A-TJ-J.D.]

Bobthetj03; if your whistle is the temperature difference from the intake and head, and this causes the gasket to leak, (and I am assuming that you mean the head gasket), could my noise be symptom of the head gasket? Mine only starts after heating up, but usually when it is cold. But! It only happens when the HVAC is engaged.


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[A-TJ-J.D.]

Oops above post in reference to Dave's, I mean Kevin Johnston's post


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[bobthetj03]

Bobthetj03; if your whistle is the temperature difference from the intake and head, and this causes the gasket to leak, (and I am assuming that you mean the head gasket), could my noise be symptom of the head gasket? Mine only starts after heating up, but usually when it is cold. But! It only happens when the HVAC is engaged.


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Sorry OP, I was just commenting on a post'ers avatar. I wish I could add something helpful to your issue, but I'm at a loss.

"Open the pod bay doors Dave."

 

[Kevin Johnston]

Bobthetj03; if your whistle is the temperature difference from the intake and head, and this causes the gasket to leak, (and I am assuming that you mean the head gasket), could my noise be symptom of the head gasket? Mine only starts after heating up, but usually when it is cold. But! It only happens when the HVAC is engaged.


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I believe mine comes from the gasket between the intake manifold and the head.

You say the shop replaced the AC/heat controls with a "junk" part? And the sound comes from a the dash? The right knob is a vacuum switch with seven vacuum lines running to it to control all the various parts of the HVAC system. If it was junk, it could be leaking, causing the whistle at low throttle or idle. I would check the vacuum system with a gauge at cold start and watch it till the engine gets up to temp, then play around with the HVAC controls and watch for any odd fluctuations. Page 1579 of the 2003 service manual has troubleshooting for the controls.

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I can probably post those pages if you need them.

 

[A-TJ-J.D.]

Sorry OP, I was just commenting on a post'ers avatar. I wish I could add something helpful to your issue, but I'm at a loss.

"Open the pod bay doors Dave."

Ha, Your tempting me, but I got a 2 year old whining at me all day, don't need my Jeep doing it too, I got to figure out what's wrong. I just hope it's not my AE-35 unit.


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[A-TJ-J.D.]

I believe mine comes from the gasket between the intake manifold and the head.

You say the shop replaced the AC/heat controls with a "junk" part? And the sound comes from a the dash? The right knob is a vacuum switch with seven vacuum lines running to it to control all the various parts of the HVAC system. If it was junk, it could be leaking, causing the whistle at low throttle or idle. I would check the vacuum system with a gauge at cold start and watch it till the engine gets up to temp, then play around with the HVAC controls and watch for any odd fluctuations. Page 1579 of the 2003 service manual has troubleshooting for the controls.

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I can probably post those pages if you need them.

Yes, post away, or send them to [email protected]. Thanks!


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[Kevin Johnston]

Your AE-35 will go 100% failure within 72 hours. I'll send those pages in the morning.

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[A-TJ-J.D.]

Your AE-35 will go 100% failure within 72 hours. I'll send those pages in the morning.

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Thanks, cause this mission is just too important for me to allow you to jeepordize it.


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[rrkohler72]

Perhaps someone can help me ID a problem with my 04 TJ. For several years my fan controller for the heat and air was stripped out or would not engage. I had a shop fix it with a "junk" part. Afterwards, the fan speeds would engage and I thought it was fixed.. However, after a time a high pitched whine began to emit from the Jeep, this only happens when the heat is engaged and Jeep has heated up.If I accelerate, the whine stops, but when I'm coasting it comes back. A few months ago, my heater hose blew and they were replaced. After that, the noise went away. But it came back in about a week, as it did the last time, the noise is getting steadily louder. If I turn off the heat or air, and turn the fan speed down it stops. This is driving me crazy, and the noise is of a particular headache inducing frequency. Anyone know what's up?


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I’m having the exact issue you mentioned. High pitched whine that only starts when the engine reaches operating temp and mostly goes away with acceleration but comes back as engine rpm’s get back to idle speed. Did you ever find out what the cause was on your jeep?