Technician A says higher than normal idle speed may be caused by an air-conditioning switch that is always closed. Technician B says higher than normal idle speed may be caused by a defective engine coolant temperature sensor. Who is correct?

Question

Quizplus · Accepted Answer

Both technicians are correct. A constantly closed air-conditioning switch can signal the engine to increase idle speed to compensate for the added load of the air-conditioning compressor. A defective engine coolant temperature sensor can send incorrect signals to the engine control unit, causing it to adjust the idle speed improperly, often resulting in a higher than normal idle speed.

Technician a Says Higher Than Normal Idle Speed May Be