I have a 1996 Pontiac Sunfire 2.2L coupe. About a year ago I was having overheating problems and replaced the waterpump and thermostat. After that, everything ran fine. The last couple of weeks I've noticed that when I am driving and come to a stop, the heater air is cool. Around 30-35 mph, the heater is blowing fairly warm air. Around 55-60 mph, I'm getting very sufficient warm air. To make a long story short, the faster the car goes....the warmer the air is blowing out the heater ducts. I'm at a loss on figuring this one out.