I picked up a second set of 20s for my non-profit's '12 Ram and installed the snows today. Since I deleted TPMS, this is extra awesome -- no concerns about 8 sensors.
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Ever since this truck was purchased new in 2012 it's had what you'd swear is blower motor noise. It happens mostly on the two highest fan speeds, and sounds a
bit like the high pitch whine you'll get over stereo speakers from interference from the charging system -- back when that was a thing.
When still under warranty the dealer replaced the blower motor, maybe even twice.....but eventually gave up and said they had done all they could.
I started chasing it today and indeed a new blower did NOTHING to cure the noise. I pulled it back out and verified it's quiet when not installed. I made sure neither squirrel cage was contacting anything. I even pulled the resistor to see if it was somehow whistling (never heard of this, but I was on a mission).
FINALLY I found that if I grabbed the HVAC box on the right side of the transmission hump and pulled it forward the noise would stop. Mind you -- the box doesn't really
move when I pull on it but more so flexes
ever so slightly. This is really nowhere near the blower motor and appears to be more of an airflow harmonics issue than a rotating object issue.
Finally I crammed a carefully calibrated piece of hardwood under the dash. This reduced the noise from a 10 to a 2. I don't really have time to chase it further at the moment.....
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If anyone has ever heard of 4th Gen Rams having a blower motor noise that was not ACTUALLY the blower motor, I'd love to know exactly what this is. Airflow is good so the evaporator is not clogged -- and remember it's been present since NEW