all it does is pump coolant to the heater core from the motor. there is 1 pump and 2 valve...one valve is for the passenger side the other for the driver side. If you remove it and replace with a "Y" or "T" fitting you will still have heat but will be hot all the time (when engine runs) and you will not have circulating coolant when off. It is true that on a hot day running the heater will help cool the coolant. Engine on or off this will circulate coolant. Check the KTMP on the OBC if it within range it is unlikely that this is your problem. Also, you should not need this to keep coolant at a good temperature...it can help reduce over heating, to turn on the heat, but that would just be treating a symptom not the problem. With or with out this the car should not leave normal range.