Prius 2010 - aircon is not cool when engine kick in

Such an issue frequently comes down to the "air mix door" (also called "blend door") inside the HVAC unit under the dash.

The door controls temperature when heating, by adjusting how much air goes through the engine-coolant-heated heater core, and how much goes around it. When you want cooling, the air mix door ought to move so that all the airflow goes around the heater core and none goes through it.

If the door is staying in the "air goes through the heater core" position, then you will have cold air when the engine is stopped, but reheated air when the engine is running.

With a bit of searching you can find a lot of threads here on diagnosing and repairing that.

 

I think in a pitch there may be a way to push it open or pull it closed whichever it needs to be but I don't know this for a fact just speaking from myriads of car experience You probably have a good bit of taking apart to do to actually get at the part but. And be careful touching every little piece under there everything will break if you barely look at it Just be very careful and work very slow there are no shortcuts these cars are built so that most everything has to come apart to get at many of the simplest things.

 

In a gen 2 you can reach the actuator by kinda standing on your head in front of the driver's seat, not taking very much apart. There are threads about this. Member yitznewton found a tool that was handy because the skid ECU was kind of in the way.

 

Yeah I'm thinking about this guy's Gen 3 I know mine is not going to be that huge of a problem matter of fact it stopped hunting for a while so I haven't done anything about it till I can yank another one off another car and clean it up and see what the real deal is tin whiskers whatever I don't know.

 

Yeah, there were some threads about gen 3 too. Some people succeeded with some inventive alternatives to a lot of disassembly—but whether those'll work may depend on exactly what's gone wrong.