2010 AC Problems - Only works when driving fast?

Eco mode is your problem. Take off eco and enjoy the cool air.

Use eco when the temperature gets cooler

 

Did you happen to notice the behavior of the electric radiator/condenser fans when you and the non-Toyota tech were poking around under the hood?

Those fans are responsible for cooling the system when you're not moving fast. At speed, ram air through the grille is enough.

Also, the outside air temperature sensor is behind the bumper cover, not far from the radiator/condenser. If you say it is reading 20° above ambient, that sounds a lot like hot air off the radiator/compressor stagnating in that space and not being sucked through.

-Chap

 

ChapmanF is on the right track, I think. Those symptoms are consistent with either the cooling fans not working, or something impeding air flow through the condenser and radiator. Did the problem begin suddenly or gradually?

 

"HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: SYSTEM DESCRIPTION (2010 Prius)". Here's the section about the ECO mode and AC performance:

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9. ECO MODE CONTROL

(a) Under the control of eco mode, the A/C amplifier restricts the air conditioning system performance under specified conditions, thus improving fuel economy.

(b) Eco mode control is activated when the ECO MODE switch provided inside the integration control and panel sub-assembly is pressed, and then restricts the air conditioning system performance as described below.

#1 Inside/outside Air Switch Control: Automatically switches the air inlet port to internal air circulation mode when the outside air temperature is equal to or higher than a predetermined temperature and reduces the power consumption.

#2 Blower Level Control: Sets the blower level in AUTO mode lower than normal, and suppresses the power consumption. (

#3 PTC Heater Control: Stops the operation of PTC heater assembly and suppresses the power consumption.

#4 Heating Restriction Control: Changes the air outlet temperature by turning the ECO MODE switch on and off during heating and increases the amount of engine-off time when the ECO MODE switch is in the on state, thus improving fuel economy.

#5 Compressor Speed Restriction Control: Restricts the maximum speed during cooling and reduces the power consumption.
=============

 

Radiator/condenser, even. Seems I can't edit old posts any more....

I missed the part about boosting the outside temp reading by 20° ... although the manual talks about reducing blower speed in ECO, that's referring to the inside, cabin blower. It would not make sense for ECO mode to deliberately inhibit the radiator/condenser fans, because that would reduce efficiency.

-Chap

 

When you first get in the hot car, the outside temperature gauge normally would show higher than actual temperature, once you start driving, the temperature reading will come down. Either way it's going to be off a few degrees, it's not perfect.

Eco mode is a pretty bad feature to enable, gas is pretty cheap to necessitate restricting your car's performance potential and cooling ability

 

i have run in eco mode since i bought it in 2012. yesterday was 96 degrees, and the a/c felt like the north pole.

nice to know about the ptc heaters, i always wondered why i couldn't feel any warmth. thanks!

when leaving the car in a hot parking lot, the temp usually reads 4-5 degrees higher than after about 10 minutes of driving.

 

I've used ECO mode since I bought the car. While there is a difference in pedal response, I haven't noticed a difference with AC. Properly working ECO mode does not do what you are describing. If it does, few would use it. I wouldn't. There's an easy to find out if ECO mode is your problem...

I think you need a blower motor.

 

The reduced ac performance is written and developed by Toyota, it's not made up

How well the ac is doing is subjective to the person using it

 

Just to clarify for others reading this forum, Eco mode does not restrict performance potential. Toyota claims full power available no matter what mode the vehicle is in, and it has been confirmed by independent acceleration tests performed in Eco and Power mode, and both deliver the same rate of acceleration.

Eco mode will alter AC performance, but I have not noticed a deficiency in cooling, granted I have spent very little time in Normal mode to compare it.