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Discussion Starter #1
126k miles on the car. about a month ago it started making a weird noise when the heater was turned on.
Kind of a eh... eh... eh... eh.... eh every 1.5 seconds. (it's hard to describe a sound) but sounds like the engine is idling rough.

the blower motor is turning on but when it's on it sounds like the engine itself is making the noise, like it's under the hood, not where the blower is. i took off the access panel to the blower and can hear the noise but it's not any louder than when i have my head under the hood.

as soon as i turn the heater off the sound goes away and the "rough idle" sound stops.

i did a search and found that it could possibly be the resistor in the blower or maybe the blower itself. trying to figure it out here before i start throwing parts at it.

can anyone help me out and point me in the right direction?
 

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It's not the resistor pack. If it were the blower or blower motor, I would think that would be pretty obvious once that cover is off & you get your ear up to it. As far as what you are hearing in the engine compartment, I can't imagine how the sound reaches into there unless it's coming through the HVAC air intake.

Another possibility is that it's actually the A/C system making the noise. Since the A/C runs in most modes, it might be the A/C compressor or clutch.
 

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a friend said that when you turn on the heater there is a sensor that is suppose to higher the engine idle, he said that could be bad (the sensor). does anyone know about this? an idle sensor...........

how can i confirm weather or not it could be the AC compressor?
 

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Engine idle is under ECM control, there is no "idle sensor" per se.

Assuming you have manual climate control, the A/C operates in defog & defrost modes only. So when you switch to either floor, bi-level or dash vents mode & the A/C button isn't engaged, the compressor won't be engaged. I probably don't need to tell you that localizing a particular sound in the engine compartment can be a real challenge, even for a pro.

If the noise is loud & distinct enough, you could try uploading a video of it to youtube so we could hear it for ourselves.
 

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I totally have the same problem, but I always thought it was just because that fan needed to be replaced... That's what it sounds like to me, but I haven't looked at it with the hood up just yet. It started happening gradually for me.
 

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Blower motors get noisy with age but generally they will chirp or squeal & occasionally will make a grinding noise. Also, the noise changes with motor rpm.
 

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Discussion Starter #7
Engine idle is under ECM control, there is no "idle sensor" per se.

Assuming you have manual climate control, the A/C operates in defog & defrost modes only. So when you switch to either floor, bi-level or dash vents mode & the A/C button isn't engaged, the compressor won't be engaged. I probably don't need to tell you that localizing a particular sound in the engine compartment can be a real challenge, even for a pro.

If the noise is loud & distinct enough, you could try uploading a video of it to youtube so we could hear it for ourselves.
so if it is the compressor, than according to what you say, i should not hear that noise when the heater is not on the defog or defrost mode? it's the wifes car and i know when she turns the heat on it's always on the defrost (very last setting to the right) mode.

I guess if i turn it to the floor and it doesn't make that noise than we could assume it's the compressor. do i have that right?
 

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so if it is the compressor, than according to what you say, i should not hear that noise when the heater is not on the defog or defrost mode?
Right.


I guess if i turn it to the floor and it doesn't make that noise than we could assume it's the compressor. do i have that right?
In floor mode the compressor is off unless you also engage the A/C switch.

Don't assume, verify. Run it over to a shop or two (definitely get more than one opinion) & let them listen to it. Shouldn't cost anything.
 

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Discussion Starter #10
update:

it's making the noise no matter what setting the heater is on, defrost or floor. so maybe i can rule out the AC compressor.

My friend said check the volts coming from the ALT to see if maybe the ALT is failing when there is a load on it. so i guess thats the next step. any other thoughts from members?
 
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