Cabin Heater Noise

[reilljp]

When the cabin heat is turned on, I hear a humming sound that comes and goes. It is not loud but has become quite noticeable to me.

If the dial is at full cold, there is no noise. If any heat is added, after about 10 minutes the intermittent humming starts. It will hum for 10 seconds or so, stop for the same, and start again. The duration is not predictable, it just comes and goes.

The noise appears to come from under the steering wheel near the door, but that could just be where the noise is being reflected.

Any ideas what this could be?



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[740GLE]

its summer, why you running heat?

You got AC on? You maybe hearing the compressor duty cycle when it's not trying to run full cold?

 

[reilljp]

Not full heat, just a little heat in the morning.

I don’t hear the AC when the temp is set to cold. I always run the AC, regardless of the temp setting.

The noise is coming from inside the car.


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[740GLE]

Right so if it was full cold, the ac will be at max duty cycle, but if you "add heat" that duty cycle is now what 50% or something? Shut the ac off and try "adding heat" see if it is the same.

Other than that, not sure.

 

[reilljp]

You are right, I turned off the AC and the noise stopped. There must be something wrong with the AC then. Why else would I hear a humming sound coming from inside the car? It’s not a AC type sound.


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[740GLE]

Progress!!! Maybe a sympathetic vibration?

Pop the hood see if you can pin point the sound with your ears.

 

[reilljp]

Update: Dealer replaced the a/c compressor and the noise is gone.


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