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Discussion Starter #1
Ok... let's see if I can describe this accurately... Vehicle is on, and in park. A/C system is operating, fan on low, driver only. I press the fan speed button "up" one notch (two segments)... I now hear a low volume rumbling noise. At first I thought there may be something in the squirrel cage, but no... the noise wasn't coming from the fan area. It was ambient...

I turn the fan back to "1", and the noise all but goes away. Back up to "2", noise comes back. I leave it on "2", and pop the hood. I hear the radiator fans operating, but that's not it. I start placing my hands on various objects to feel for a vibration. I place my hand on the coolant reservoir over the converter, and feel a vibration. I put my ear to the reservoir, and I can hear it. I then turn the fan back to "1", and listen again... sound reduced by about 80%. Back up to "2" to verify, and sound came back the same as it was before.

Whatever is going on, the sound is transferring into the cabin. It wasn't there couple hundred miles ago. I understand that when increasing the fan speed, you're increasing the load, and the system has to keep up. And, I understand vibration can travel from one component to another, it's just that the coolant reservoir was the most accessible.

Is there any known issues with the converter cooling system? Coolant pump? Anything about the converter I should know about? There are no trouble codes, and everything operates... it's just that noise/vibration that's giving me pause for alarm...
 

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I cannot figure out why the inverter would have a higher load causing noise and repeatable from a couple watt increase on the blower fan.

I assume you have tried the same settings with the AC off, different vent direction, and higher fan speeds? This will help rule out any standing wave issues inside your vents that can cause noise.
 

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I cannot figure out why the inverter would have a higher load causing noise and repeatable from a couple watt increase on the blower fan.

I assume you have tried the same settings with the AC off, different vent direction, and higher fan speeds? This will help rule out any standing wave issues inside your vents that can cause noise.
I agree. Sounds like an acoustic OR mechanical vibration issue not an electrical issue.
 

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Discussion Starter #5
I cannot figure out why the inverter would have a higher load causing noise and repeatable from a couple watt increase on the blower fan.

I assume you have tried the same settings with the AC off, different vent direction, and higher fan speeds? This will help rule out any standing wave issues inside your vents that can cause noise.

It only happens when I turn the a/c fan motor to the second segment. If the noise/vibration would be "100%" at the second segment, the first segment would be "25%". The noise/vibration at the coolant reservoir will remain a constant from the 2nd segment, all the way to "high".

With the a/c off, the noise/vibration is "0%". The return coolant tube at the reservoir has a stronger flow of coolant when the fan is turned to the 2nd segment, so, that's why I was asking about any issues with the coolant pump, being electro/mechanical...
 

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I have had this exact same problem twice. Each time I had just had service in which the shop removed the cabin air filter. Each time it was a leaf flapping inside the squirrel cage. I know you said you already checked, but it's very difficult to clean out the squirrel cage, and it might be worthwhile to investigate it again, maybe using your phone camera to peak inside. The low rumble I had didn't sound like it was coming from the cage, but was fixed both times when I removed just the right debris from the cage. Best of luck!
 
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