The third generation Toyota Prius front cooler has two cooler modules. They fixed together but somehow dust can reach the space between them, and causes a loss of cooling efficiency. Sometimes it leads to cylinder head problems. After 200 000 km you should look into the coolers and clean if its necessary.
Step 1: Preparing
You will need a gardening water jet and a vacuum cleaner. I made some extension to my vacuum cleaner to reach the dust in the bottom. Duct tape solves everything :)
To disassembly the front part you will need a flat screwdriver (for the clips) a 10mm and a 12mm socket.
Step 2: Disassembly the Front Part - Remove the Clips
Remove the upper cover by pushing the center of the plastic clips. You have to push back the clip center to the normal state before reinstalling them. Remove the clips which holds the top of the front bumpers. These clips can be removed by lifting the center of them using a flat screwdriver.
Step 3: Disassembly the Front Part - Remove the Front Bridge
Loose and remove all the screws which holds the front bridge. It has a tricky screw on the front side, but it must be removed too. Remove cooler supports and the inverter support.
Disconnect the lock bowden but don't forget to connect during the reinstall then you can't open the hood if you forget to reconnect it!
You can now remove the front bridge.
Step 4: Disassembly the Front Part - Remove the Two Cooler's Cover
Loosen the two screws of the plastic cover which joins the two cooler radiators. Pull it up and now you can see the hell between your radiators. Let's clean 'em up!
Step 5: Clean the Coolers
Use the vacuum cleaner to suck the dust between the radiators. A soft brush may help to remove the feathers, dry leaves and the dead insects from the radiator platelets. I made some water jet based cleaning process to wash out the dust. Someone uses a high pressure water cleaner, but be careful: high water pressure may damage your cooler! You can use some insect remover spray before flushing the radiators.
I found a lots of leaves, dead insects, complete bird feathers and also a cigarette. I don't know how they get into this place but these things were there.
I hope this "operation" will prevent my car from cooling and cylinder problems.
Step 6: Reassembly
Do the same backwards, and don't forget to reconnect the lock bowden before you slap down the hood!
Easier to fit the front bridge when you don't tighten the screws before you install all of them.