According to your profile you have an '11 RAV, as I do. The major difference is that yours has the I4 engine and mine has the V6. My heating system doesn't act in the same way as yours does. Since your system throws out more heat in sharp turns, a guess would be that there may be air trapped in your heater core. If so, the remedy is to purge the air from the system. From a 2009 post by our esteemed administrator JuneBug:My car is same since new. it take about 8 to 10 mile to start warming up the cabin even the motor is at 186F after about 2-3 miles. It is not very comfortable. I have heard, the new RAV has an electric pre-heater. If it is true, probably Toyota knows this "problem". And I noticed, when I do sharp turn, left, or right, hot air sharply fills leg area, and at straight it is again cool till 8-10 miles of travel.
I have a 2010 RAV4, this time last year on start up the heat would kick in fairly quick. Now it seem to take quite a while to get the interior warm. If anyone could help thanks in advance.