So my vehicle is at the dealer right now and I explained what's been happening with the vehicles heating system after extended driving time (usually the problems surface when I've been driving the vehicle on and off or on long drives for about 2 hours).

First it started with a noise and normal heat/cool air pumping out.

Then -as you can see with my video below-


my heat was making a noise but right after I turned it off the air just stopped blowing out all together. It has since returned. Anyhow I've complained about this issue twice and the dealer has only been able to suggest a coolant fluid exchange stating that it could be due to low coolant or coolant that is clumping and drying up since my RX has 101,000 miles on it.

Based on research I've done it sounds like its probably the motor and nothing to do with the coolant. Anyone else ever have this problem?

 

Lexus/Toyota hybrids do not power the compressor with an accessory belt as with conventional
IC engines. This permits A/C (and Power Steering) when the engine is off while driving at low
speeds or stopped. Additional advantage is that compressors are efficient at a narrow range of
RPM, your home and business HVAC units run at a constant speed with 220 v., the hybrids use
the 280 v traction battery to power the unit. A belted compressor is forced to build up a high start
up head pressure while the IC motor is idling in traffic and then subjected to extremely high RPM
(2+ times engine RPM...8,000 RPM?) when it is just maintaining a steady pressure.

Touch the console menu and select Climate. Try the A/C button both when the system seems to
be working and then when it quits. There is an electric motor driving the compressor and you
ought to hear and feel a difference. Low refrigerant pressure will trip a sensor to avoid damage.
Low engine and or hybrid system coolant would not seem to affect any of this A/C condition.

 

Just an observation.
1.as mcomer said, hybrid has electric, not belt driven AC compressor. But I think, you are trying to turn on heat?
2. there is an issue with heat to be produced for hybrids on RX and Highlander hybrids. That being, engine is source of heat by virtue of its operation. ICE runs= heat is produced. Well, what produces heat in a hybrid when you are rolling in EV mode or moving from electrim motor? Nothing. ICE does not run. Temp gauge drops down.
On Camry hybrid Toyota did smart move. They placed PTC heater as part of heat exchange unit inside the car. Hence, if there is demand for heat, PTC heater turns on and in matter of less than a mile you have full blast heat.
For some reason unknown to me, Toyota chose not to do same on SUV hybrids.
But, heat has to be produced, right? It's December. What they did then is they force ICE to turn on and off to produce at least some heat. When I take off in cold car and then stop at say red light, I can feel engine turn on/off, on/off. Peculiarly, engine will NOT show on MF display as running. Like they are ashamed of it, or something.
That said, you WILL feel a jerk and noise, when ICE is forced to kick in.
I don't think it's issue you are experiencing but... Thought I'd mention it.

 

Sounds a failing blower motor to me.
Noise from either bearing or contactor in electric motor.
In my cases in other vehicles I've faces squaking sound in cold start but also sudden failure with no warning when contactor is worn out
http://www.rockauto.com/en/catalog/lexus,2010,rx450h,3.5l+v6+electric/gas,1444314,heat+&+air+conditioning,blower+motor,6916

I undestood you manually control the fan speed in the video, the fan should react to manual control whatever is the heat status.
If cabin temperature is already in the set temperature, no extra heat is needed and thus ICE stays stalled .

Have you checked/replaced you interior cabin filter reguraly? Dirty filter will stress the motor to do more work except in recirculation (as you have set on)