In stop n go driving you will have the fan pop off and on frequently. If the fan does not turn on, you will need to replace it. This should happen as the high side of the system approaches 214 psi. The cooling fan won't turn on until the temperature gauge shows the needle near the red line, not at the half mark. Radiator fan testing points. If I open the panel and spin the squirrel cage a little, it immediately begins to blow air and runs the heating cycle. The ECT sensor monitors the coolant temperature, and allows the fan to turn on if the coolant is too hot. When the A/C is turned on, the fan moves air across the A/C condenser, thereby removing heat from the vapor refrigerant inside. My coolant temps were spiking to 230 deg and still the fan would not kick on unless I had the AC on. The compressor clutch does not engage. @ Tallra1 I already checked the wirings, and its all in good shape, but i havent check yet the main thermo-switch. Cooling fan wont turn on 6 Answers. Ac wasn't blowing cold air. Found out the cooling fan wasn't running when the ac was on. My thermostat signals the heater correctly and the burner ignites, but the fan doesn't always turn on. Small cars typically have stacked AC and engine radiators cooled by a single fan. The display inside the SUV says A/C on and the engine rpm does change when you press the A/C button. Photo: an electric motor using a pulley and belt to drive the fan in an air … Then it goes to the radiator. Fuse 31 is not blown. Step 4 – Check the engine coolant temperature (ECT) sensor. Figure 3. Temp was getting way too hot. The A/C does not blow cold air. The relay looks fine but do not have another similar one to try. Fan ran and ac was cold for two weeks. 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. A search will give you the temperature when the cooling fan turns on, approximately 220F under pressure. Problem solved. Poor air conditioning performance. The temp between operating temp and fan is like 20 degrees apart, so yeah. - Mike. If the radiator fan is in working condition, move on to the next step. If the a/c doesn't run then the cooling fan isn't needed. What could this be? The engine cooling fan does not turn on. The reason being, on most vehicles, is that the cooling fan doubles as a condenser fan. 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. Find an Air Conditioner Service Professional Near You. 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. @johnblack I checked it while it is on cold state, but then when turn the AC ON the Radiator Fan turn on, so I let the AC ON while i drive my car, after 30mins driving if i turn the AC OFF, the RADIATOR FAN still dont work, even the Radiator Temp was hot. You are looking to see if the PCM sends power to one or both relays to turn on the coolant fans. Replaced the fan. A faulty cooling fan relay can also negatively affect air conditioning (A/C) performance. I noticed my cooling fan stopped working and would only come on when I had the AC on. 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. That depends on the car.