If I manually start the driver side fan by spinning the blade with my finger, it then runs (AC still on). I have a 1998 Ford Mustang Cobra 4.6 with a DOHC. to nonvtec: One fan is for A/C, and the other for radiator. Faulty Fan or Clogged Radiator comes to mind when talking about other reason why car overheating when ac is on. Why Won't a Radiator Fan Turn On? Temperature Sensor . Now from what your saying that your temps are getting high while driving on parkway then you have a flow problem either the thermostat , radiator ,water pump or even a bad head gasket can cause that . If the fans go on then your temp should start to come down to 200 and fans should shut off . AC and defrost is off. The engine fan shouldn't come on right away because the goal is … At least until around 2009, as was noted earlier, if the engine is overheating, then the radiator fans should run regardless of whether or not the AC compressor is connected, or is turned on. The main problem is that, when I turn on the AC the Radiator Fan turn on as it should, but then after a while it turns off and the car overheats. What I have found so far: Fan does cycle at medium or high speed with AC or Defrost turned on. Fan does not turn on at any other time that I know of, or that I can hear while driving. It only comes on when temperature rises to operating range. One note on the fans. I saw in a couple posts about air pockets in the cooling system and when the fan should come on, so I decided to let it run. If the A/C fan still comes on, then it is not the relay. The cooling fan should come on immediately or within the next couple of minutes. 2012 eco. The AC fan should start when you turn on the AC. If you have two fans, they are controlled by the AC, and the Engine's specific needs, automatically. On older vehicle models, just wait about 15 to 20 minutes for the engine to reach operating temperature. The condenser fan usually has smaller blades and more of them. Shouldn't radiator cooling fan be … read more I'm aware that the AC won't cool as well when idling or at low speeds - compressor turns slower and less airflow over the condenser, etc.. I don't know which one is the radiator fand and which one is the condenser fan since I can't find the condenser. My car started overheating on about ten hours into a fifteen hour trip. by Richard Rowe . No overheating problem at all. I have to turn the A/C on medium fan setting in order for the engine fan to cool the temps back down to 200-210. 2006 PT CRUISER - NON-TURBO. Your air conditioning creates extra work, and heat, for yur engine. - 2005 Chrysler PT Cruiser If the A/C fan … I bought a preowned s320 recently, and notice that the radiator fans started to turn about 5 seconds after ignition switch is on, and even before starting the car. 2013 F150 AC & Cooling fan issues - 2013 F150 5.0 XLT 153,000 miles This past summer the AC was blowing warm. When driving, temps stay between 199-209. When I run the AC is really lugs the motor, but that might be normal or a separate issue. Image by Flickr.com, courtesy of Peter Morgan. FAN IS SET TO AUTO = FAN runs automatically ONLY when compressor or furnace is running. 2 Answers. This depends on the circuit that manufacturer has used, in some cars the radiator fan will switch ON only once the AC radiator fan has heated up to certain temp. For the radiator fan, there is a relay and a fuse. When you turn the AC on, both fans should turn at the slower speed and I believe that both are then fed though the condenser fan fuse (#58). You can visually check the fuse. The condenser fan is the smaller of the two. (Recommended) FAN IS SET TO ON = FAN runs AT ALL TIMES regardless if compressor or furnace is running. You may want to check those. It seems like I could always hear it running when I pulled into the garage when the AC was on. Radiator fan does not come on when the temp gauge hits the halfway mark (it's usual spot to kick on), but comes on immediately when I turn on the AC, and once that happens the car returns to normal operating temp. With engine at idle/operating temp and parked, AC and defrost not turned on: Fan does not turn on at all. I stopped, changed the thermostat (because the heat was blowing cold, thought it was stuck shut.) My cooling fan is not acting as it should. This small structure can wear out after prolonged use. to nonvtec: One fan is for A/C, and the other for radiator. A car's electric cooling fans are responsible for ensuring air flow over the radiator at low speed, and failure will almost always cause overheating while in traffic. 1) Its ok, but neednt cut in immediate also. This is pretty much an open and shut case for a bad radiator fan relay, right? The ECU’s job is to start the radiator fan once the engine reaches a certain temperature. The ECU gains information from the sensor, which signals to the ECU to turn on the fan at the correct time. Seeing the fan won't turn on in city driving the ac doesn't work well at all. Toyota Camry 2004 radiator cooling fan only runs a few seconds while AC is on. The check engine light is on and the code says coolant temperature is low. Nope, fan is in auto amd mode is heat , heat comes on and so does the outside unit.not a heat pump , also i am getting 22 v at C and Y …at C and W i am getting 24.7v … it should be a bad tstat..but when i jump off at board with tstat in off mode.Y to C , heat also comes on with out side unit. A new fuse (#57) may let the radiator fan run for a while, but I believe it will eventually blow. WIth a meter it looks like most everything checks out. @ Tallra1 I already checked the wirings, and its all in good shape, but i havent check yet the main thermo-switch. Sometime it might be that your radiator is not bad, but it could have been clogged which makes your car overheats as you on the AC when you are driving slowly or while on a stationary position. For the Coolant Fan Thermal Switch mounted which is mounted in your radiator (which triggers fan operation when the AC is not switched on), the only things connected to it are the Fan Control Module which controls the operation of your fans, and the battery through some fuses. But the engine fan will come on only when the computer tells it to. As for the relay, I would swap the radiator relay with the A/C relay (they are the same on 2007 Accord). With this in mind they decided that the fan should preempitively come on any time you use your AC. @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. A condenser in a car air conditioner ensures that you get cool air from the vents of your air conditioner when you turn the AC on. Fans only kick on when AC is ON. Turning AC off doesnt stop fans Only turning off the truck stops them. My car has a manual transmission. The "Engine radiator fan" and the "Ac radiator fan" are one-and-the-same on 95% of vehicles. (Not Recommended) Setting the FAN to “ON” is not needed to run the AC or HEAT. If so, I changed the low speed rad fan relay and it still won't run with a/c until the engine thermostat turns it on. Set your air conditioning to the MAX setting and turn it on. On your yr crv I believe it is on the passenger side. Once you replace the relay, the radiator fan should start working again. Radiator fan only comes on when Ac is on. This is during 60 degrees outside temp. While sitting in backed up traffic, temps based on the digital dash go up to 226. My Radiator Fan not turning On, when A/C is activated otherwise it works fine when the coolant sensor gets to the correct temperature. Generally, I understand that radiator fans should start only after coolant or engine temperture reaches a certain high temperature, and when cooling is required. It's toyota camry 2004 XLE 4 cylinder. Radiator fan might wait even longer for the coolant to reach a certain temperature. If this connection went bad on its own, the high temperature switch would still make the fan come on when it heated up. These past few weeks have been brutally cold and I've noticed the cooling fan starts working as soon as I turn on the car. Cooling Fan Not Working with AC On Thanks for the diagram! no, when the AC is on they both seem to work , even when the temp goes up, or if you turn off the AC , then the fan stops turning. THe fan actually came on at 214 F. So I … In other words, they turn on when they are needed without your intervention. For the radiator fan, there is a relay and a fuse. It takes a long time for the engine to heat up. As for the relay, I would swap the radiator relay with the A/C relay (they are the same on 2007 Accord). Fortunately, these systems are fairly easy to diagnose in the event of failure. (2004 Honda Civic) I'm having issues, and am at a deadlock. When I get on the highway then the AC works. Then, the fan should come on. I found underneath the Thermostat housing a single wire going into the engine block, is this the sensor switch. When AC is on, Radiator fan does not come on. This morning it was 32* and i noticed that i could hear my radiator fans running wide open. The second time the fan comes on is with your AC. I have no picture to tell if I'm on the right trail. You can visually check the fuse. When exactly this happens is different for different cars. should the radiator cooling fan always run when the a/c is on? When the thermostat is set to “ON”, the FAN will run at all times. The radiator fan should come on. You may want to check those. Let the car cool down, and finished the trip with no problems. Turn the AC on and the electric fan on the radiator should run. I think it has a radiator cooling fan issue. My car has been over heating when my AC is off.The radiator fan turns on when my I turn my AC on, but then the car starts to heat up when I turn off the AC which also turns off the fan,causing it to over heat. Anyway when I turn on the AC, only the one on the passenger side starts. Yes, it's the condenser fan in the front of the radiator/condenser. My car has 180502 miles. The fan should turn off after the engine is shut off. If you have two fans. On many Hondas, both fans turn on when the AC is first turned on and the compressor is running and temp set to low and heater/AC fan turned on. If it does the relay is working. Connection went bad on its own, the fan comes on when they are needed your... 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