My cooling fan won’t turn on when I turn the ac on. Relays and fuses are good, tested the fan with the battery and it came on??
My cooling fan won't turn on when I turn the ac on. And when I do turn my ac on the car seems to get hotter..it had reached 230°f at one point, but I got no lights saying it overheated, and I never let it go higher to see. Now running tests with the car in park and I can't get it to go past the normal temp, about 198°f for my 08 hhr. But the fan still isn't coming on at normal temps either. We did replace the fan, used, and after we did that the ac clutch quite making noise, but still movement. The relay clicks when we put 12vts to it. And the fan works off the battery. All the f
Experienced mechanics share their insights in answering this question :
Hi there. In general, a situation like this occurs when either the thermostat housing or temperature sensor is not relaying the information to the fan motor to activate. However, it’s also possible that there is some electrical short within the cooling system relay’s that is causing the fan motor to not activate when it should. I think the best way to determine the precise source of this problem is to have a professional mechanic come to your location to complete an onsite inspection so they can test all systems to help isolate the root problem and recommend the right repairs.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
If the AC unit fan is not spinning, the first thing to check is the circuit breaker. Take a look at the circuit breaker associated with the AC unit and see if it`s been tripped. A circuit breaker may trip from overheating due to outside temperatures and the motor`s heat.
On most modern cars, the cooling fan is controlled by the Engine Control Unit (ECU) which gets a signal from the coolant temperature sensor. If it`s not working, the fan won`t turn on when it needs to, which means the engine might overheat.
The most likely culprits are a thermostatic switch, fan resistor, temperature switch, low-speed or high-speed relay, or a wiring issue.
Well the short answer is yes. The A/C requires the fan to run as part of the heat exchange process. The A/C runs on a separate circuit and is triggered by A/C system.
Here`s an easy way to test if the fan`s capacitor is bad.
If the fan takes off and then keeps going on its own, you more than likely have a bad start capacitor. You took over its job of kick-starting the fan by pushing the blades. If the fan doesn`t start running, you may have a bad fan motor.
The cooling fan relay is the relay that controls the engine`s cooling fans. When the correct parameters are met, a temperature switch or the computer will activate the relay, which will allow power to the fans.
The engine temperature should trigger the fan to turn on. It will also turn the fan off once the engine has cooled to under 200 degrees. You may have heard of a part called the radiator fan switch or temperature fan switch. This is linked to a thermostat and works much like your home`s HVAC system.
Depending on the type of radiator fan your car has, it may be powered by a built-in electric motor or directly by your car`s engine. Either way, it uses a thermostatically-controlled device that turns on the fan when the coolant reaches its safe maximum temperature.
An unlikely, but possible, cause is a bad thermostat. Try turning the Fan switch to the “On” position to see if the blower comes on.
There is no set time as the cooling fan works on temperature. If the coolant goes above a set temperature the fan comes on and does not go off until the lower hysterisis set point is reached.
Delivering torque to the fan motor, if the capacitor is faulty, there won`t be enough power delivered and the blower wheel, fan belt, and other important components can cease to operate.
1. What happens if the capacitor fails in the fan? If the capacitor loses its efficiency, the fan will receive power. Since the start coil gets affected, it won`t develop enough torque to start the fan.
The capacitor can be tested by using a voltmeter. The voltage rating of the capacitor is used to test the capacitor with this method. The voltage is mentioned as 16V, 12V, 50V, etc., based on the maximum voltage a capacitor can tolerate. The capacitor is charged for a short time and the power supply is disconnected.
Can I Replace an Air Conditioner Capacitor Myself? The short answer is no. AC capacitor replacement should only be done by a licensed AC technician as there are risks involved.
In most vehicles, the cooling fan uses the same sensor as the one on the engine coolant, which means it also relies on the PCM for input. If the PCM receives the wrong signal from the ECT sensor, it can stop the fan from working and cause the engine to overheat.
Temp Sensors
The Coolant Temperature Sensor is used to measure the temperature of the engine coolant. The readings from this sensor are then fed back to the engine control unit (ECU). This data from the sensor is then used to adjust the fuel injection and ignition timing.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
My cooling fan won’t turn on when I turn the ac on. Relays and fuses are good, tested the fan with the battery and it came on??
ANSWER : Hi there. In general, a situation like this occurs when either the thermostat housing or temperature sensor is not relaying the information to the fan motor to activate. However, it’s also possible that there is some electrical short within the cooling system relay’s that is causing the fan motor to not activate when it should. I think the best way to determine the precise source of this problem is to have a professional mechanic come to your location to complete an onsite inspection so they can test all systems to help isolate the root problem and recommend the right repairs.
When I turn on my AC the radiator fans do not turn on. The fans do come on when the car warms up so I know they are working and the fuses are good. The AC compressor does come on and the air blows ice cold when the car is moving. Car is a 2006 Chrysler Sebring Sedan 2.7l v6.
ANSWER : The control circuit for the fans needs to be checked. For example, there is usually a condenser fan relay in the A/C electrical controls. There could be a fault with that relay and/or wiring problems, perhaps even just a loose connection, blown or loose fuse, and so forth. To resolve something like this, the recommended service is an electrical component diagnostic. If you request that diagnostic service, the responding certified mechanic will get the problem pinpointed and resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Just replaced my fuel pump but its not getting any power tested fuel pump relay and fuel fuse both good tested the wires all good.
ANSWER : You need to look at the theft light on dash to make sure it comes on and goes off when you turn the key to the on position. If light comes on and stays on then your theft system is causing the fuel pump to not be engaged. I recommend you check the theft system and then scan the computer for theft system codes. You may need to reprogram the keys to work or you have an bad sensor for the ignition key in the steering column.
replaced cooling fan switch, relay, thermostat fan still won’t come on even with AC running
ANSWER : It sounds like you’ve taken all the right steps, so I understand if you are frustrated. If you look in the fusebox again, you might find a fusible link that powers the fan if you haven’t already checked that. Most late model cars activate the fan via the ECU which activates the relay, so you are at a point where diagnosis may require a scan tool that has the ability to do activation. You can have that checked right there on the spot by contacting Your Mechanic. They can send a technician to your home or office to check out your cooling fan and let you know what it will take to solve your problem.
Car cranks won’t turn over, fuel pump not turning on but was remove and tested it has power and is working. Fuses good relay good.
ANSWER : There can be a sensor or electronic control unit (ecu) issue. If for example, the crankshaft sensor is faulty, the ecu may not see engine revolution when you’re cranking. If either due to a faulty crank sensor, or ecu, the crank sensor signal is not being read, the ignition and fuel pump systems will not power up. Also, a faulty ignition module can create the same issue. Check for signals from the crank sensor and other sensors. If you still have the issue, then have a certified technician look into the no start condition to find the exact cause.
Battery saver system car won’t turn and battery good and starter. Whole dash illuminates when I turn key though, no alter
ANSWER : Have the battery load tested in case it was short circuited. Reverse polarity, at the battery, in a 12 volt electrical system on a car can cause a variety of effects including damaging the alternator, diodes and the numerous microprocessors on a vehicle such as those in the powertrain control module (PCM). There are fuses, fusible links, circuit breakers, and many electronic components in many circuits that could have failed due to the reverse polarity. Inasmuch as the vehicle does not start, the simplest thing to do is diagnose the starting circuit first as, in the course of that diagnosis, other fundamental failures (for example if the PCM was fried) will come into view. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
A/C compressor clutch does not engage, cooling fan does not turn on, condenser fan does not turn on, and ceiling light does not turn on.
ANSWER : Hi there. The air conditioning clutch could be not working for the refrigerant could be low or the clutch could be burned up. Check the air conditioning compressor clutch wiring for a voltage with the a/c switch on high and fan on high. If there is a voltage present then the clutch is burned up and needs replaced. If there is no voltage present, then the system could be low on refrigerant or the low or high side pressure sensor has failed. If there is voltage to the sensors and nothing past the sensors, then the system is low on refrigerant. If there is no voltage to the sensors, then the a/c switch would need to be replaced.
The cooling fans and condenser fans either are not coming on from a loss of power or the motors are burned up. First check the cooling fan circuit. If there is no power to the cooling fan, then check the fuses and see if they are burned. If the fuse is good, then check the cooling temperature sensor / switch. If the sensor has power to it an after, then the switch is working. If there is no power after the switch, then the coolant temperature sensor / switch would need replaced. If there is power to the motors on the cooling fan, then the fan motor is burned up and needs replaced. For the condenser fan, if there is no power to the fan, then check the fuses for any of them burned. If the fuses are good, then the a/c switch would need to be replaced. If there is power to the motor, then the condenser fan motor is burned up and will need to be replaced.
For the ceiling light (courtesy light) is not working when the door is open, then there could be an issue with the bulb being burned or the switches are damaged. First check to see if the light is just turned off. If the light is on the door settings, then check the doors one at a time and see if the door courtesy light switch is broken, stuck, or has a loose or corroded ground. If the ground is good and there is no problems with the switch wiring, then I recommend replacing the door courtesy light switch.
For the parking brake light always on, check to see if the parking brake lever is all the way down in the unlock position. If the lever is all the way down, then check the parking brake sensor on the parking brake lever and see if it’s working.
If you need further assistance with the issues your are facing, then seek out a professional, such as one from Your Mechanic, to help you with the following:
air conditioning compressor clutch not working
cooling fans and condenser fans not working
courtesy light not working with the door open
parking brake light always on
My truck cut off the other day while driving. Battery is new and good, check relay and its good. When I turn the key it won’t move?
ANSWER : Have the battery tested professionally if you have not already done so. A battery can show 12 volts while the car is off, but drop to a low voltage while trying to start the vehicle which is a sign the battery has failed. The alternator is responsible for maintaining the charge on the battery, so if the alternator is not working properly, the battery will drain and cause the vehicle to stall.
With a failed battery, there may be enough voltage for the interior to light up, but not to start the vehicle. Usually, if the ignition switch fails, nothing comes on. If you want to have the fault identified by an expert, a certified technician from YourMechanic can come to your car’s location to determine why your vehicle will not turn over and perform any repairs.
