It still makes the same noise with the third row seat heating on or off? If it is coming from the interior behind the panel I believe there is only the HVAC housing under there. But the housing is a complete heating/AC unit with all the necessary bits to operate / possibly malfunction to create you "Electronic Squeal" sound. Removal of the Remove right rear quarter panel trim would be helpful to pinpoint the issue.
Rear heating/AC unit parts:
A/C expansion valve
Temperature control blend door actuators
Rear blower motor resistor
I didn't think to change the rear heating settings... I cannot make any connections as to why HVAC would be impacted by engine load, but I'll give it a whirl by changing some of the settings that are in the rear and report back if it makes any differences.
The sound is almost certainly coming from the right rear in or around the seat or panel.
You are right, it is odd about the sound not being there when just reving the engine without load. Usually any electrical/coolant sounds change with reving of the engine with or without load but if the sound is coming from behind the rear trim there isn't much left
I had a bearing go on our old minivan but it got progressively louder with speed and was independent of the load from the engine. That is why I thought transmission instead of the bearings. It could possibly be that the sound is more pronounced and noticeable when the rpm and sound from the engine go down which could take it back to the bearing. It is a weird one. Good luck. I am definitely not a mechanic and don't even play one on TV and didn't stay at a Holiday Inn Express.
I tried turning on the rear heater unit, but it didn't make any difference. A couple other points. This is a very High pitched whine like what you would hear from a High Voltage transformer. It only kicks in when the RPM of the motor reaches 1800 and is under a load. When I did start up the rear AC unit, with the blower going, it helped in that the sound is coming from somewhere in front of the rear blower but it is definitely on that side.
Still unable to locate the exact location, however a new data point is that with the unusual high temperatures (we will see 70 degrees in DC today) I can report that the squeel is still there. So temp is not a factor.
Here's an update...
Early this morning (5:00 AM) I started off to work with the High pitched squeel as I drove up the street. Lately, I have been trying to get the Air pressure the same in all tires, and the right rear was showing 2 pounds over the others. I pulled over and in those early morning hours, when all is still and quiet, and with the motor off, I bent down to pop the stem cap. With my ear just in front of the rear wheel, I could hear some lower frequency sound coming from just in front of the rear wheel but near the bottom of the Jeep.
I'm wondering if it is related to my other problem, but don't have any idea as to what is located just in front of that wheel.
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