My friend has a 1997 Cavalier SL 2.2L that has a strange problem. When she is driving the car under normal conditions whether moving or stopped, she has no overheating issues. Additionally, when the car is moving and she turns on the heater and blower the car still doesn't overheat. However, if she come to a stop for more than a minute it starts to overheat. If, when stopped, she turns off the heater and blower, the car cools back down. Does this make sense to anyone? As background, she has had overheating issues in the past three month and has had lots of work done to include the replacement of the water pump, thermostat, radiator flushed, hoses reseated and the system checked for blockages, coolant drained and refill using vacuum.