what's a inverter coolant reservoir?

Air conditioning is weak/non existant on my 2008 toyota prius. So now i get to play mechanic, the car has what looks like two coolant reservoir as indicated on this page - http://www.mytoyo.com/topr-170-checking_the_coolant_level.html. The "engine coolant reservoir" is straight up empty, looked around and didn't see any signs of leaks. While the "inverter coolant reservoir" is a bit low, is this one the over flow? I can just add coolant into the engine coolant reservoir until it is full and be good to go?

Sorry if this is a stupid question. I learned wrenching on a volvo 240 and this Prius is very complicated, tight spaces, and making me want to keep my Volvo as a daily driver.

Inverter coolant cools the device that turns DC power (batteries) into the AC power that runs the electric motor.

Has nothing to do with engine coolant.

An inverter is a device that turns DC into AC. Batteries make DC, and the electric motor in the Prius is an AC motor (I think), so it needs an inverter to make it run. They aren't 100% efficient, so some of that power gets wasted as heat, and it sounds like it has a separate cooling system for it. Electronics like to run at lower temperatures than internal combustion engines, so that makes sense.

Ok, then i will fill both reservoirs back to full.

Only use OEM coolant, especially in the inverter reservoir. Using the wrong fluids in those cars can cause catastrophic failure. I've heard of incorrect A/C oil destroying the inverter system.

NEALSMO wrote: Only use OEM coolant, especially in the inverter reservoir. Using the wrong fluids in those cars can cause catastrophic failure. I've heard of incorrect A/C oil destroying the inverter system.

Ok, ill go to the toyota dealership then.

Cool, the upshot is i just took out spark plug #1 to put in new Denso plugs and it looks like the spark plugs were changed a little bit ago already. As the plug was NGk and that's not OEM.

Look for signs of slow seepage at the water pump weep hole. It can lose coolant without anything ever hitting the ground if the leak is slow enough.