tried to set temp at 22c to 24c, outside temp was 18c, but no heat, nor warm air came out from the vent. cold air all the way (at least 30 minutes drive). set it to 30c and higher, then I can feel the hot air. i just found out from here the prius's heater performance is not good. but that bad? is it normal or should i bring it back to toyota to look at it?
The heater in the Prius works just fine. Even in Edmonton. It does take the engine a little longer to warm up when the car is idling. When driven it warms up quickly. You should get warm air in the conditions you list, and fairly quickly if the car was already warmed up. Do remember you won't get warm air out of the centre vents. Check the side vents and do watch where the car is venting the air (the symbol on the system that indicates floor, upper, or both).
What was the cabin temp like when you started? The climate control system compares the temp setpoint (22c) to the cabin temp (not outside temp) and will increase cabin temp until it reaches setpoint. If your cabin was already warm it will not be blowing warm air. It sounds like when you raised the setpoint to 30c and began feeling hot air that the system is working fine.
cabin sure was not up to the temperature yet because a 22c cabin should not be that cool in an early morning. just talked to a service guy in toyota and scheduled to check the temperature sensor next week.
At 18C outside the car may well be at 24C inside. There is a heat source in the cabin (the driver plus any passengers) and during the day there is solar energy coming through the windows. Secondly, if the incoming air feels cool, it does not necessarily mean that it is not heating. The incoming air is in motion and can be a long way above 24C yet still feel cool on your skin. To check if it actually is above cabin temperature, you need to put a thermometer in the airstream.
