Gen 3 Prius outside temp sensor inaccurate

When you're standing in front of the car with the hood up look down in between the AC condenser and the outer or inner portion of the front bumper cover you'll see a little piece of plastic sticking forward off of the center support that splits the radiator in half or looks like it does It's the part the hood latch is attached to also It's a cross bar that runs up and down right in the middle of the radiator and condenser this bar at the very bottom of it has the temp sensor plugged into it It could have been moved and come disconnected and be laying against the radiator fins or such.

 

The only time I see the ambient sensor lower than expected is when it is wet.

 

It is fairly common for that temp. reading to be "inaccurate" but it usually reads higher than
ambient rather than lower.

Since that has absolutely NOTHING to do with the operation of the car, I suggest that you wait a while before
you do anything about it.

 

Ambient temperature is an input to the AC system’s neural network.

 

Did that information come from Toyota.......or NASA ?

I have seen NO evidence that the AC system on any car I have ever driven is anywhere
NEAR that sophisticated.

If it did come from Toyota, what models is it supposed to apply to ?
Certainly not all of them.

 

It’s one of those top secret Toyota TIS documents called the Repair Manual for the gen3 Prius.

 

how long is 'awhile'?

 

The algorithm takes the outside temp (ambient), uv radiation (solar), room temp(cabin) along with evaporator temp and several other realtime points (including engine and inverter temps) to determine the system capacity and airflow needed or allowed.

This computer controlled, variable capacity, integrated system was groundbreaking in 2004 for any vehicle much less standard in an economy car. The three phase electric compressor has proven to be very reliable and can output max capacity while the vehicle is parked with the engine off. Far more advanced than 99% of our residential systems even twenty years later.

 

Yes but is that sensor the SAME one that produces a reading on your dashboard ?
Somehow I doubt it.

 

Yes. Why would they have two?

 

Because they serve two ENTIRELY different purposes.
And likely the "fancy neural network" needs a different kind of input than the dash readout does.
That is, if you believe the hype.

 

Knowing the ambient temperature is an ENTIRELY different purpose from knowing the ambient temperature?

The sensor behind the front bumper is a thermistor and wired to the ECM.

The HVAC controller is on the CAN bus, and says "hey ECM, what's the ambient temperature?".

In a Gen 3, the outside temperature that you see, you see on the HVAC controls display, and that's how that number gets there. (In Gen 1 and Gen 2, you saw it on the MFD, so there was an extra "hey, what's the ambient temperature?" step involved.)