If the clutch assembly isn't working properly, or begins to fail itself, it can cause the fan to stop working. Over time, the clutch assembly will begin to wear and require servicing. Inspecting the clutch assembly for your cooling fan should be a part of routine care for your Volvo. If the fan runs, you probably have problems with the relay or the temperature sensor. The temp sensor is just below the thermostat in the lower thermostat housing near the power steering pump. The attached diagram show you the wiring for our Volvo> Hope this helps, good luck. If the fan does work when the engine is hot but does not when A/C is switched on, then could be either low refrigerant charge, bad pressure sensor, or bad compressor/clutch. I'm not sure what you are referring to as the 5 A ECU fuse, but it can't be the fan power source as this is far too low to support the fan. It is possible that the wires and connectors are faulty. If you notice that the fan does not work even when the car is overheating, there might be a wiring issue or a bad connection. If this is the case, you must fix them. You should check the wires from the control unit or relay to the radiator fan. Your volvo fan relay is a two stage (speed) relay. It constantly has a 12v feed. As soon the ECU provides low or high speed ground signal to it, it will energize the fan accordingly. Have you started noticing that your air conditioner isn't running quite as cool as it once did? There's a chance that this is related to a defective volvo fan relay. Volvo XC70 Radiator Fan Not Working? RepairPal will help you figure out whether it's your Fan Assembly, Fan Clutch, Coolant Temperature Sensor, or something else. Symptoms of a Cooling Fan Module Failure. A problem in the cooling fan module will not go undetected in your Volvo because of the important role that it plays. Some of the symptoms that you will notice immediately when this problem occurs include: An overheating engine. When the cooling fan module fails completely, the cooling fans will not 2004 Volvo s60 2.4L I5 Cooling Fan Replacement Explanation. I was pretty sure I had correctly diagnosed that my Engine Cooling Fan / FCU (Fan Control Unit) were bad, but I wanted to make sure You can test things by grounding, one at a time, the relay pins associated with the yellow and the yellow/white wires that go to the center of the cooling fan relay. One should turn the fan on high speed and the other should turn the fan on low speed. If that works then the fan and the relay are good. L2N3z.