Why does the engine fan keep coming on and off?

Why does the engine fan keep coming on and off?

The engine fan will only stay on for a few reasons. Mosf of the time the fan clutch solenoid is bad. It is an electric solenoid that turns the fan on and off. You can find it by following the air line that comes from the fan clutch hub. In you case, it may be the A/C high or low pressure switch since you are getting an A/C trouble code.

Why does my Peterbilt a / C compressor not shut off?

The thermal switch would be at the evaporator, but I don’t recall your truck using one. It’s possible that you have a bad expansion valve and being covered up by an overcharge of refrigerant. law3tkm Thanks this. I have never been able to replace just the clutch on a A/C compressor on a Peterbilt. Peterbilt always says it can not be done.

How do you turn off an engine fan?

There are two high pressure switches, one to cut out the compressor and the other to signal the ECM to turn on the fan. Open circuit to the ECM means high pressure, once you jump it to trigger low pressure, (assuming the pressure is faulty), the ECM will count down about 2 to 3 minutes before it will actually turn off the fan.

Is there a fan in the engine compartment?

No, it is in the engine compartment, it is a sensor. A bad fan clutch solenoid is usually the first thing to look for but could be several things.

Why is the solenoid on my fan not working?

The solenoid is normally powered up to pass air to the clutch to keep it from engaging. This problem is occurring when the solenoid is powered down. It is a block and bleed function where it blocks the supply pressure and then bleeds the output going to the clutch to cause it to engage.

Can a solenoid be replaced on a fan clutch?

Replacing the solenoid soon (found it on fee bay “Parker 8204 0459-45 24v-dc Solenoid Valve 0524473Z”), but I needed to drive hundreds of miles today through the SLC inclines. The tap method worked out great! One curious thing – I have two solenoids side by side, same specs.

What should the pressure be on a solenoid fan?

It should release it immediately when the solenoid is powered down. Pretty much must be a defective unit since it says it is rated for 140 psi. No way the wet air is that high of a pressure. Air keeps the fan off no air th fan should come on. Reverse from the m939 trucks.

Why does the ECM keep the fan on?

the best thing is take it to the dealer have them hook it up and see why the ecm is holding the fan on. The ecm sends power to the solenoid to shut the fan off. Dont rule out the a/c if the expansion valve gets pluged it will hold pressure for a long time which can keep the fan on. tkilby Thanks this. Having a great time with TMC.

Can a cat engine keep the fan on?

Cat engine..fan stays..the solenoid and the ac valve and it stills on… I have 05 kw t800 heavy haul. C15 cat problem is fan Will I have 05 kw t800 heavy haul. C15 cat problem is fan Will NOT shut off can you tell me which sensor and where It is that controls fan clutch thank u … read more Vocational, Technical or Tra…

Why does my Peterbilt fan not go off?

I have a 2004 peterbilt with a c-15 engine. When the outside I have a 2004 peterbilt with a c-15 engine. When the outside temperature goes below a certain temperature like -15 celsius the engine fan engages and won’t go off. What would cause this to happen? … read more

Where is the fan on a Peterbilt 379?

If nothing can be seen with the service tool, you most likely have a faulty fan control solenoid, fan hub, or broken fan control wire that runs from the engine ECM. It is on pin 11. Basically, the ECM sends out 12 volts on pin 11 whenever the ECM wants the fan off. When the ECM wants the fan on, it removes the 12 volts from pin 11.

What are the symptoms of a bad cooling fan relay?

1. Engine running hot One of the first symptoms commonly associated with a bad or failing cooling fan relay is an engine that runs hot or overheats. If you notice that your engine is running at higher temperatures than normal, that may be a sign that the relay is not functioning properly.

Why are my cooling fans running at all times?

3. Cooling fans stay on at all times. If the cooling fans are staying on at all times, this is another (less common) symptom of a possible problem with the cooling fan relay. If the relay shorts internally, it may cause power to be permanently switched on, which will cause the fans to run at all times.

When do you turn on the fan relay?

When the correct parameters are met, a temperature switch or the computer will activate the relay, which will allow power to the fans. The relay will usually be activated once it is detected that the vehicle’s temperature approaches excessively high temperatures.