drivers side heat
 

the heat on the drivers side is cooler than the passenger side. also the heat only gets really warm when i rev the engine. i tried the bleeding process but it didnt seem to make a difference. I just got the car and dont know if the water pump is plastic. I imagine it has been changed out as it has 180k on it. also the temp guage seems to be right at the half way point most of the time yet heat not blowing hot. anyone with any ideas that can help?