In this video, young mechanic Aiman will give you ideas and show you how to bleed the INVERTER coolant system loop to get rid of trapped air bubbles in a Gen II Toyota Prius Hybrid Synergy Drive I4 1.5L car. Second generation Prius vehicles includes model years 2004, 2005, 2006, 2007, 2008 & 2009.
So why would you have to bleed the inverter coolant loop? Perhaps you replaced the parts such as the pump, hoses or even radiator. In this video, Aiman explain how the air bubbles can form, and what happens afterwards. If there's air bubbles in the system, the coolant will get pushed out into the reservoir or expansion tank and finally into the ground. Getting rid of trapped air bubbles is critical to inverter and must be done to avoid overheating and potential damage to the transaxle system.
Read more about Inverter Cooling System below:
The inverter cooling system is completely independent of the ICE (Internal Combustion Engine) cooling system. It uses a separate radiator and water pump, and it operates at a lower temperature than the ICE cooling system (We also have a video on how to bleed the ICE coolant system which involves re-cycling the coolant through the Heat Storage Tank Canister by turning on and off the CHRS relay.
The Prius transaxle system, with its use of heavy-duty motor/generator units, is no exception to this rule. Temperatures get so hot under the hood that the vehicle requires a dedicated cooling system to prevent catastrophic damage to the stator windings. This is where the inverter coolant loop comes into the picture. It functions separately from the engine cooling system, though they both use the same type of compound to control operating temperatures.
The inverter loop includes a brushless 12V electric pump to circulate coolant through the baffles of the Prius transaxle. This fluid absorbs heat from the inverters, then flows past the engine’s electronics, cooling them in the process. It releases heat to the surrounding air as it passes through the vehicle’s radiator, then returns to the bafflers for the next cooling cycle.
While this may sound identical to how a conventional engine cooling system works, there are important differences between the two. The inverter cooling loop does not have a thermostat, for example. Also, it keeps the coolant at lower pressures than its counterpart.
The Prius uses an independent cooling system to keep the inverter and motor/generator (M/G) at a safe temperature. In warm weather, problems with the inverter cooling system are fairly common in both the Gen 1 Prius (2001-2003), and Gen 2 Prius (2004-2009). The inverter cooling system uses the same type of coolant as the ICE cooling system. Gen 2 was factory filled with Toyota Super Long Life Coolant (SLLC). SLLC is premixed, eliminating the hassle of mixing and the potential for error.
Servicing the Inverter Coolant Loop
While some object to the complexity of its layout, in truth, this supplementary cooling loop does a good job of protecting the Prius transaxle from heat damage. Of course, nothing lasts forever, and these systems eventually develop a host of problems. Typical issues include:
Air pockets forming in the system: These can be removed by using the built-in bleeder system to flush out old coolant, but fixing the underlying problem means replacing defective components.
Pump failure: This can be diagnosed either by removing the cap of the expansion tank and checking for circulating fluid or by touching the pump housing while the Prius is running. If it fails to vibrate, then the pump is not working. Some Toyota pumps have shown sub-par performance over the years; check the service updates for the particular vehicle you’re working on.
Low fluid levels or use of non-standard coolant mixtures: Toyota is very clear that only its formulas should be used for cooling the Prius transaxle. Unfortunately, the desire to save a buck or two means that some owners or shops use inferior products. When this happens, the results can range from poor heat control to outright vehicle damage.
Thanks for watching. This video is presented to you by young mechanic Aiman-Imran Zulhilmi Anuar. Please watch Aiman's other DIY auto repair how-to remove, replace, install, repair, fix-it, tutorial, guide, tools review etc on his EyeOnAiman youtube channel. We hope the video can be helpful in your DIY auto repair endeavors for your trucks and vehicles. Car manufacturer always recommend that you use genuine OEM parts, but alternative aftermarket parts can be cheaper and readily available at local auto parts stores such as Advanced Auto Parts, O'Reilly, AutoZone, NAPA, Pep Boys even at Walmart or Home Depot. And if you're not comfortable doing the repair yourself, please take you car to a local mechanic, certified garages or dealer-ship.
Recording Date: November 29, 2018
Video URL: • How To Bleed INVERTER ...