1) Its ok, but neednt cut in immediate also. 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. On older vehicle models, just wait about 15 to 20 minutes for the engine to reach operating temperature. 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. The radiator fan should come on. You can visually check the fuse. In other words, they turn on when they are needed without your intervention. 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. 2 Answers. While sitting in backed up traffic, temps based on the digital dash go up to 226. This small structure can wear out after prolonged use. @ Tallra1 I already checked the wirings, and its all in good shape, but i havent check yet the main thermo-switch. My car has a manual transmission. When exactly this happens is different for different cars. My cooling fan is not acting as it should. Then, the fan should come on. Set your air conditioning to the MAX setting and turn it 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. When the thermostat is set to “ON”, the FAN will run at all times. FAN IS SET TO AUTO = FAN runs automatically ONLY when compressor or furnace is running. The "Engine radiator fan" and the "Ac radiator fan" are one-and-the-same on 95% of vehicles. I think it has a radiator cooling fan issue. Image by Flickr.com, courtesy of Peter Morgan. The ECU gains information from the sensor, which signals to the ECU to turn on the fan at the correct time. When AC is on, Radiator fan does not come on. As for the relay, I would swap the radiator relay with the A/C relay (they are the same on 2007 Accord). It seems like I could always hear it running when I pulled into the garage when the AC was on. 2012 eco. Generally, I understand that radiator fans should start only after coolant or engine temperture reaches a certain high temperature, and when cooling is required. My car started overheating on about ten hours into a fifteen hour trip. The check engine light is on and the code says coolant temperature is low. 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. For the radiator fan, there is a relay and a fuse. to nonvtec: One fan is for A/C, and the other for radiator. Radiator fan only comes on when Ac is on. You may want to check those. 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. 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. When I get on the highway then the AC works. 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. When I run the AC is really lugs the motor, but that might be normal or a separate issue. The cooling fan should come on immediately or within the next couple of minutes. You can visually check the fuse. The condenser fan is the smaller of the two. 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. On your yr crv I believe it is on the passenger side. @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. The fan should turn off after the engine is shut off. by Richard Rowe . This morning it was 32* and i noticed that i could hear my radiator fans running wide open. Once you replace the relay, the radiator fan should start working again. 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. WIth a meter it looks like most everything checks out. should the radiator cooling fan always run when the a/c is on? 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. 2006 PT CRUISER - NON-TURBO. Yes, it's the condenser fan in the front of the radiator/condenser. If it does the relay is working. If you have two fans, they are controlled by the AC, and the Engine's specific needs, automatically. The AC fan should start when you turn on the AC. 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.. But the engine fan will come on only when the computer tells it to. 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. Anyway when I turn on the AC, only the one on the passenger side starts. (2004 Honda Civic) I'm having issues, and am at a deadlock. (Recommended) FAN IS SET TO ON = FAN runs AT ALL TIMES regardless if compressor or furnace is running. I have a 1998 Ford Mustang Cobra 4.6 with a DOHC. 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. (Not Recommended) Setting the FAN to “ON” is not needed to run the AC or HEAT. 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. No overheating problem at all. I stopped, changed the thermostat (because the heat was blowing cold, thought it was stuck shut.) With engine at idle/operating temp and parked, AC and defrost not turned on: Fan does not turn on at all. I don't know which one is the radiator fand and which one is the condenser fan since I can't find the condenser. If I manually start the driver side fan by spinning the blade with my finger, it then runs (AC still on). If the A/C fan … Faulty Fan or Clogged Radiator comes to mind when talking about other reason why car overheating when ac is on. This is during 60 degrees outside temp. Why Won't a Radiator Fan Turn On? I have no picture to tell if I'm on the right trail. The second time the fan comes on is with your AC. Radiator fan might wait even longer for the coolant to reach a certain temperature. As for the relay, I would swap the radiator relay with the A/C relay (they are the same on 2007 Accord). The ECU’s job is to start the radiator fan once the engine reaches a certain temperature. 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. Your air conditioning creates extra work, and heat, for yur engine. Fortunately, these systems are fairly easy to diagnose in the event of failure. If you have two fans. One note on the fans. 2013 F150 AC & Cooling fan issues - 2013 F150 5.0 XLT 153,000 miles This past summer the AC was blowing warm. What I have found so far: Fan does cycle at medium or high speed with AC or Defrost turned on. If the A/C fan still comes on, then it is not the relay. 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. Fan does not turn on at any other time that I know of, or that I can hear while driving. Seeing the fan won't turn on in city driving the ac doesn't work well at all. When driving, temps stay between 199-209. AC and defrost is off. It only comes on when temperature rises to operating range. THe fan actually came on at 214 F. So I … Toyota Camry 2004 radiator cooling fan only runs a few seconds while AC is on. Cooling Fan Not Working with AC On Thanks for the diagram! 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