AC CONDENSER FAN full speed continually 199% DUTY CYCLE

[MRSSPOCK]

Could anyone please explain to me what a 199% duty cycle means on an AC condenser fan, (as reported by live data from the scan tool).
The fan on this FORD FOCUS is running non stop, at what appears to be full speed. (I am assuming there is no speed control on such fans, but rather are on or off ?)
I'm trying to diagnose why this is happening, and the only data I can gather is that this fan runs at 199% duty, from the live data.
Does it mean that it is constantly running at twice its intended speed, or running twice as long as it is meant to at its full duty cycle?
The above fault happens regardless of AC being activated or not, and regardless of demister being activated or not.
So it is not a case of refrigerant being too hot at the evaporator sensor, since this occurs right away, (after about 1 minute), first thing in the morning, even after the car has been sitting cold all night, and with the magnetic compressor clutch not even activated).
The fact that it takes 1 minute before this fan kicks in would suggest that a relay hasn't jammed in the on state.
Thanks

 

[GregLocock]

199% is ridiculous, my guess is that is what is being requested by the control circuit. I'd take an uninformed guess that it thinks the pressure is too high in the refrigerant circuit.

https://www.youtube.com/watch?v=Wt4Pl0r2prs

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[MRSSPOCK]

I just bought a gauge and intend to put it on in a day or two when I get back where the car is. Thanks

 

[3DDave]

Top several answers based on South Main Auto Repair (am an avid fan of is diagnostic work)

#1: The 199% is because the software is not entirely compatible. Turns out car companies don't always publish accurate information for 3rd parties to use. Sometimes their own diagnostic software is wrong.

#2: Bad ground leading to an abnormally high reading because a sensor is trying to short the reference voltage to ground and can't - instead of reading 0V it is now reading 5V or 12V.

#3: Corrosion allowing a 12V power wire to leak current into a sense wire - sometimes at a connector, sometimes where a mechanic nicked multiple wires getting the protective tape off to try to find another problem.

#4: Bad sensor that may have a small crack in a solder joint or wire. When power is first applied there is some heat generated in the sensor until the sensor warms up and the crack opens up and it looks like #1 but in a place you cannot find it.

#5: Per some videos the fan has a fan speed controller, which is why there is a "%" reading at all rather than "on" and "off". It is possible the fan speed controller has failed with a shorted condition to the transistors controlling the fan speed - as I recall from seeing a very expensive system try to flail itself to death from shorted transistors.

 

[MRSSPOCK]

Thanks for all those possibilities. I will give an update when I get some results. Thanks

 

[MRSSPOCK]

I still haven't had a chance to get back to solving this problem, but for now I just have the fuse pulled, and there is no big panic. But what I have found, when I decided to pull the fuse, that the fuse is labelled as the intercooler fuse, so at least know I know the official purpose of that fan. I have also since learned that this car has an active front grill, and also that it does not perform its initial start up routine, when the car is switched on. Because it doesn't pass this reference test at start up, the system can only presume the worst, and in doing so, it turns the fan on full speed. I have got hold of the wiring diagram and can see that the active grill is controlled by a BUS network. Next step is test the BUS line for communication then power and ground at the actuator, once I get a chance to do it. Hopefully I will give an update soon. Thanks

 

[sunnysky]

199% would be an overflow measurement possibly with no cycles and just DC full ON.