Better way to bleed inverter coolant?

Nothing you did it just right It's a mag drive pump most of these things The impeller's not attached to a shaft that penetrates the seal and goes into the electric motor so you're not hurting it if it runs dry for half a second or you know a minute even shouldn't hurt it if it gets to an overheating point it would shut off which would take some time I usually just do what you did I feel the I change the pump hook up all the hoses fill the reservoir and then before I turn the mess on I kind of squeeze the hoses like a milk and a cow that go to the pump and I can even feel the coolant while I'm squeezing and letting go and squeezing and letting go I can feel the coolant moving through the hose and when I feel that happening then I actually start to see the reservoir go down a little I don't do anything about it at this point I might squeeze one or two more times again and then ready the car The pump I hear running it's making funny noises like it sucking air and sucking little coolant squeeze the hose again once or twice and then all of a sudden you get that lot of r noise and then it goes quiet in the jug drops now you top it off and you're done there's nothing to worry about anything burning or blowing up I don't think they've changed the design of the generation 3 pump much from the generation to type and design I'm sure it's a different shape or whatever no matter I've actually done this to the persona once pretty much for no reason I wasn't changing the inverter pump.

 

Maintenance Mode is not the way to go. It is used for engine coolant replacement, but inverter coolant replacement is different, simpler. This @NutzAboutBolts video explains (fast forward to around 3:00 to skip preliminary steps). The Repair Manual concurs (excerpt attached), but the video is much clearer.

In a nutshell, you refill to the reservoir top line, put the car in Ready (fully on, one push of start button with fut on the brake), for just a few seconds ((not long enough that engine starts), then stop, check coolant level (it should drop some), top up as needed, and repeat a few more times, till coolant is stable, at the top line.

 

I did both engine and inverter coolant a few years back, For Inverter I followed the video (and Repair Manual), did not use Maintenance Mode, and no problems.

@NutzAboutBolts also has a engine coolant change, but that video is somewhat at odds with Repair Manual (excerpt attached). In the video, they run maintenance mode with the reservoir cap off, a funnel in it's place. The Repair Manual advocates to fill to the B line (somewhat higher than the full line, then cap it and run in Maintenance Mode till fans come on twice.

It also suggests (in my bootleg copy) to open the engine coolant vent while refilling. This a knurled, white plastic cap on a black plastic junction, just above the EGR components (and half-buried under the cowl). Your 2012 likely doesn't have this vent. What you could as a workaround would be to pull off one of the hoses going into that junction, leave it off while filling till coolant flows out.

It's debated here whether that vent is needed. I'll pay more attention the next time I do the engine coolant change, but I do recall as I was refilling, at some point coolant started coming out. Which to me says that prior to that there was likely air coming out, displaced by the rising coolant level.

 

So they stopped using the inverter air purge valve when they updated Gen3 Prius?
Is so that makes sense because the one on Gen2 is just barely necessary.

 

Not familiar with gen 2 inverter coolant. I’ve got the repair manual though, could take a look and post excerpt if you want. I’ve probably already made the excerpt; will have to check.

there’s no mention of vent for 3rd gen inverter coolant; there was one for engine coolant, but just for first m/y or two.

 

Here's gen 2 inverter coolant change, and yes, they mention vent. Attached engine coolant too:

 

No better way than what we’ve been doing. Also, be on the look out for the inverter water pump replacement video