Replaced the fan. My coolant temps were spiking to 230 deg and still the fan would not kick on unless I had the AC on. Radiator fan testing points. What could this be? The engine cooling fan does not turn on. Photo: an electric motor using a pulley and belt to drive the fan in an air … The A/C does not blow cold air. If I open the panel and spin the squirrel cage a little, it immediately begins to blow air and runs the heating cycle. Figure 3. A faulty cooling fan relay can also negatively affect air conditioning (A/C) performance. This should happen as the high side of the system approaches 214 psi. The reason being, on most vehicles, is that the cooling fan doubles as a condenser fan. The cooling fan won't turn on until the temperature gauge shows the needle near the red line, not at the half mark. Poor air conditioning performance. You are looking to see if the PCM sends power to one or both relays to turn on the coolant fans. Fan ran and ac was cold for two weeks. @ Tallra1 I already checked the wirings, and its all in good shape, but i havent check yet the main thermo-switch. If you have a situation with a central air conditioner fan not working and you have exhausted the troubleshooting steps outlined previously, it’s time to schedule an appointment with a certified HVAC technician. If you use the ac it will run on low then as the engine needs cooling it will burst into high speed and back to low as needed. Ac wasn't blowing cold air. If the fan does not turn on, you will need to replace it. Find an Air Conditioner Service Professional Near You. When the A/C is turned on, the fan moves air across the A/C condenser, thereby removing heat from the vapor refrigerant inside. That depends on the car. If it exceeds this amount of pressure and the system doesn’t turn on, one of the sensors in the system that the PCM uses to know when to turn the system on and off has failed. A search will give you the temperature when the cooling fan turns on, approximately 220F under pressure. If the radiator fan is in working condition, move on to the next step. The relay looks fine but do not have another similar one to try. Problem solved. If the a/c doesn't run then the cooling fan isn't needed. The temp between operating temp and fan is like 20 degrees apart, so yeah. The ECT sensor monitors the coolant temperature, and allows the fan to turn on if the coolant is too hot. Cooling fan wont turn on 6 Answers. The compressor clutch does not engage. Found out the cooling fan wasn't running when the ac was on. Temp was getting way too hot. Fuse 31 is not blown. My thermostat signals the heater correctly and the burner ignites, but the fan doesn't always turn on. I have a similar problem and cannot find my specifics after doing a lot of research and forum reading, so I hope someone here could help me. Step 4 – Check the engine coolant temperature (ECT) sensor. 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