We have fixed a number of faults where the car runs fine at normal or high speeds but as soon as the car comes to a stop, it begins to overheat. At times, the cause of this condition is not very obvious and can be difficult to trace.
Things that can cause a car to overheat when idling are as follows:
Fan speed - It is possible for this to happen because cooling system fans are designed to run at variable speeds. The implementation varies in different cars. Some cars use 2-speed fans operation, some use 3-speed fan operation, some use pulse width modulation technique for varying fan speed. Let's take the 3-speed fan as an example. If a relay, fuse or wire that controls the low speed operation is faulty, fan will work well when there is more cooling demand but will not work ..