climate control issue

[Takimo]

so i told my trusted mechanic these 2 problems, #1) i always wait temp gauge to reach middle before opening heater, but as soon as i open heater, the temp gauge drop to 1/4 to the cold side, and it slowly get up to the middle.



#2) no matter i put the heater 20 degrees , 26 or the maximum 32... it always feels like it blow extreme hot , like 60degrees ...



he told me it was the thermostat and coolant sensor, he change the part but the problem still here... anyone can help ? could it be the climate control unit ?? please help