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Discussion Starter #1
hi need help on my radiator fan is not turning off automatically like it used to be.

it all started when my radiator had a leak and has been changed brand new with new coolant. I already flush my radiator and change new coolant but still problem exist.

correct me if im wrong... before when my ac is on I used to hear a clicking sound or a trip off which means the fan turns off and on alternately for every 5 min.. but after I change my radiator the trip off has gone.

what seams to be the problem is it the CYLINDER Head Temperature sensor? or radiator thermostat switch?

Thank you..
 

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...before when my ac is on I used to hear a clicking sound...
The clicking sound is the A/C clutch engaging and disengaging. It would not be normal for the fans to make a "clicking sound", so are you sure you are not confusing the sound of the A/C clutch and the fans?

Your fans should come on shortly after you turn on the A/C when the car is not moving. They come on as refrigerant pressure builds up on the high side of the A/C system.

Can you give us a better description of what is happening?
 

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Discussion Starter #3
hi thanks by the way. I don't think its the clutch.

my problem is the ac is not automatically kicking on and off.. its always on once you turn it on.

im not sure if that's the case about car ac? before I change my radiator I can hear a kicking sound.. Im not sure if its the ac compressor or the fan that's turning off and on.
 

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...my problem is the ac is not automatically kicking on and off.. its always on once you turn it on...
Okay, if I am understanding you correctly, the A/C is staying on all the time. If this is the case, it is possible that you are just low on refrigerant. Does the A/C cool properly, or is a little weak?

Oh, welcome to the forum.
 

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Discussion Starter #5
yes thats correct ac is staying on all the time..

My ac is cooling fine in fact the mechanic just add refrigerant in it.. but still it stays on all the time.
 

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...the mechanic just add refrigerant in it.. but still it stays on all the time.
If this started with the A/C system being serviced, then I suspect that the charge needs to be rechecked. With an undercharge the A/C compressor will tend to stay on (clutch engaged).
 

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If this started with the A/C system being serviced, then I suspect that the charge needs to be rechecked. With an undercharge the A/C compressor will tend to stay on (clutch engaged).
Actually, no, a low charge will usually cause the clutch to cycle on/off as the low side pressure drops too low to safely operate, a proper charge will generally cause full time operation on the clutch, as all the pressures stay in the safe range, and high side pressure is kept below the high pressure shut off by fan operation. ....I'd say your fan is working correctly, turn off the a/c, and the fan will likely shut off shortly after
 

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Actually, no, a low charge will usually cause the clutch to cycle on/off as the low side pressure drops too low to safely operate
Only as the charge drops lower. If the system is leaking (and I suspect it is because the OP just had it charged) the pressure on the high side cannot be maintained. So, the compressor stays on. Eventually the refrigerant charge drops low enough that the compressor begins to cut out.

...a proper charge will generally cause full time operation on the clutch, as all the pressures stay in the safe range, and high side pressure is kept below the high pressure shut off by fan operation...
Nonsense. It is normal for the compressor to cycle to maintain the system pressure. It even cycles more if you operate on lower blower speeds than higher speeds.
 

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Only as the charge drops lower. If the system is leaking (and I suspect it is because the OP just had it charged) the pressure on the high side cannot be maintained. So, the compressor stays on. Eventually the refrigerant charge drops low enough that the compressor begins to cut out.


Nonsense. It is normal for the compressor to cycle to maintain the system pressure. It even cycles more if you operate on lower blower speeds than higher speeds.
If you say so, I guess 20 years as an ASE master tech working for Ford doesn't mean a thing these days


I will say, in addition to what I said before, that at high ambient temps, the system may cycle, but at 70-80 degrees, it is likely that the compressor will run constantly
 

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It's not nonsense, dave89iroc is correct. Once you charge high enough the compressor quits cycling at idle and stays on, it WILL cycle at highway rpm but may never at idle. How I charge mine now. It pretty much stays on 100% of the time at idle. I get there somewhere around 280-300 highside at over 95 degree day, somewhere in there the clutch quits cycling at idle and a good place to stop charging. I watch for it specifically. If you don't go that far you're throwing away some cooling there.

I used to have trouble with that idea as well, thinking it would blow the compressor up having done that before. These though operate somewhat differently, you can have clutch on at idle 100% and as long as they cycle a bit at speed you're fine. Got 3 cars running around like that for years now.
 

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...Once you charge high enough the compressor quits cycling at idle and stays on, it WILL cycle at highway rpm but may never at idle...
Absolutely correct there!

However, testing pressures and proper A/C operation should be done with the car set up to do so...about 1,500 RPM, high blower, doors open, a "normal" outside temperature, etc. Sure, the compressor clutch may not cycle at idle, but checking A/C operation at idle does not tell you too much and a "master tech" should know that.

This forum and others like it have many discussions about clutch cycling being normal such as: http://www.focusfanatics.com/forum/showthread.php?t=290029). Magus was spot on when he said "The AC compressor Clutch will cycle as needed to keep the low pressure and high pressure switches "happy". How much it cycles (its duty cycle) will vary depending on the outside air temp, your blower speed, and the charge of the system."

When charging a system, I usually idle the car until I get a decent amount of refrigerant in the system and then raise the RPM to finish and test. While filling, the clutch initially short cycles due the low charge, but as more refrigerant is added, there is the zone in which the charge is enough to prevent low pressure cut out, and yet not enough to cause high pressure cut out and the compressor stay on. This same area is reached when the system is leaking refrigerant before the charge comes down enough to start short cycling the clutch.
 

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I personally feel the 1500 rpm thing is a crock and a farce. The car does not idle at 1500 but a/c performance will be better at higher rotational speed, in short, a Ford copout to make systems seem to be working better than they are. They've done that for years to avoid warranty claims.

I disagree with this............'checking A/C operation at idle does not tell you too much'. It is at the highest heat load point there is, the compressor is turning slowly, if cooling then it will pretty much cool like h-ll at other speeds. Tell me how many complain to Ford about car not cooling at idle in traffic???? SCADS........and how many complain it doesn't cool at 1500 rpm? NADA. The cars don't even stay at that rpm long enough to tell and another reason why they picked it. To throw complainers off their ballgame by pitching in a red herring standard.

Once again, it's Ford vs. the real world..................

LOL and no insult intended at all.
 
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