Why is the diode on my focus fan not working?

The purpose of a diode is to prevent electricity from flowing in one direction while allowing it to flow in the other direction. This is so that your fan motors don’t push electricity into the system backwards. Find the fan diode, remove it, and test for resistance. If you don’t get any, then test it with the leads swapped.

Why do my fans go on when I unplug the PCM?

Answer: Unplugging the sensor causes the PCM to default the coolant temperature as -40 degrees F. This is why the fans go on. Normally this means that the wiring and the PCM (which turns on the fans) is functioning.

Can a diode be used to turn on a fan?

By putting the diode between the new switch and the ECU, the ECU is still able to complete the circuit and turn on the fan but cannot detect that we’ve manually completed the circuit on our own. Without the diode, the ECU may be able to detect that the circuit has been completed and may throw a code indicating a failure of the cooling system.

Why are the fans not working on my focus?

The fans will not come on until the engine is at 115C. You can’t test the fans without the engine being hot. There should also be a fan diode. Diodes are tricky to diagnose. You can do a resistance test, but a diode will only show resistance in one direction.

Is the Ford F150 radiator fan always on?

@bhurry yes they are loud but for as long as your temp is good the fan is working properly. No, that is not related to the resistor. The fan does turn on with the AC it is designed like that. Just a heavy duty fan…. I have the same problem and I have never in my 29 years ever heard any truck fan as loud as mine and ac sucks

Why is the AC not working on my focus?

Since your AC doesn’t work, let’s assume it’s due to a low charge. Unplug your AC clutch, and secure the connector somewhere out of the way so it won’t get caught up in the belt. Now find your low pressure switch which should be on top of the accumulator which is in the fender under the passenger side headlight.

What are the symptoms of a bad cooling fan resistor?

Another symptom of a potential problem with the cooling fan resistor is cooling fans that stay on at all times. If the resistor shorts or fails, it can cause the cooling fans to stay on even when they are not supposed to.

What is the function of a cooling fan resistor?

This is made possible by routing their power through the cooling fan resistor. The cooling fan resistor is an electrical resistor that limits power to the fan in steps, so that the fan can operate at different speeds according to the cooling system’s demands.

Why is the resistor on my Ford Escape not working?

For example, as you can see in this photo, the blower motor resistor in this Ford Escape has failed due to corrosion. If the resistor shows no visual damage, the resistance between terminals must be checked and compared to specifications. If the resistance is out of specs, the resistor must be replaced.

What happens when you turn off the cooling fan?

In certain cases, the cooling fans may even stay on when the vehicle is turned off, and will create a large parasitic drain that will eventually kill the battery. The cooling fan resistor is an important component, as it is one of the components that routes power for the cooling fans.

Why is the diode on my focus fan not working?