1998 F 150 4.6 V8 - AC Clutch Cycling

redwoolard · #1 09-08-2009, 08:02 PM

My AC is blowing plenty of cold air but the clutch is cycling on the ac about every minute or so.
I only have a small gauge that came with a can of freon but it is showing on the high side in the green range.
Could it be the cycle switch and where would it be located?

The AC will freeze you if you leave it on. Another thing, the ac clutch will cycle on and off, no matter where you have it set, panel, floor max ac - doesn't matter where you have it.

Register today or sign-in to remove these ads!

Bugman1400 · #2 09-08-2009, 08:34 PM

You either have a clutch going bad or your system is overcharged. Probably the latter.

projectSHO89 · #3 09-08-2009, 10:14 PM

Quote:

Originally Posted by Bugman1400

You either have a clutch going bad or your system is overcharged. Probably the latter.

I don't agree. It is perfectly and completely normal for the clutch to cycle at an interval that is dependent on, among other things, the ambient temperature. There is a cycling interval vs. temperature chart in most service manuals that should be referenced.

The only thing reported that is abnormal is that he said the clutch will cycle in outlet selector positions that are not consistent with the design. The compressor is enabled in ALL selector positions EXCEPT OFF, FLOOR, and VENT (PANEL). If it is in fact operating in any of those three positions, then the system has a fault such as a bad selector switch or EATC, depending on what is installed.

Bugman1400 · #4 09-10-2009, 08:09 PM

I'm not familiar with a '98 model as far as the EATC. Perhaps your right about the cycling...I was thinking the high pressure cutoff was being tripped since it seemed like he may have added a can or two. However, if that was the case then the cold air would not be maintained. It would turn back to non-conditioned air until the pressure dropped back to normal. Since he is talking about freezing then it is most likely the ACET sensor and it doesn't have much to do with ambient, only evap temps. Where is the Ambient temp sensor, inside the cab or outside? If outside, is it the same one that feeds the dash display for outside temp or is that a different sensor?

redwoolard · #5 09-10-2009, 08:59 PM

I haven't added any freon to the system. It has always cycled regularly but it seems like it is a lot more often than it used to be.
I don't think this model has an eatc.
What does the cycling switch do? I read somewhere that they get out of range sometimes and would make the system do this. I know it has a cycling switch because they list one as a part.

I did check out the ac compressor, a little closer and the compressor will stay off on panel or floor position but I usually switch to panel/floor and it stays on in that position. I guess I just thought that it would stay running in every position if it ran in the panel/floor position. I knew it always ran on defrost.

The ac stays cold, especially for south georgia so it probably isn't low or high pressure unless a switch is bad. If you couldn't hear the clutch cycling so often, I would not think anything is wrong.

Bugman1400 · #6 09-14-2009, 10:47 PM

I'm not totally familiar with the '98. My 2005 can have A/C on any setting. Also, mine does not cycle. What I thought maybe happening is that your pressure may be getting too high and tripping the high pressure switch. I've seen these go bad. I've also seen where people over-charged there system by adding more and more freon when the problem was actually a clogged condensor. If your system is properly charged, then you can tell if it is a bad high pressure switch by jumpering the switch. If the compressor stays on and stops cycling then the problem is the switch. The best thing for you is to use a proper set of gauges or take it to a mechanic who has gauges. I highly doubt it will cost you that much since your compressor is definitely good.

Yankee7985 · #7 09-14-2009, 11:23 PM

The cycling switch is on the accumulator which is at the firewall. You can R&R it without loosing freon.

projectSHO89 · #8 09-16-2009, 08:04 AM

Ya know, it actually sounds like your system is working properly and that there is nothing wrong with it.

Every "symptom" you have described is normal.

redwoolard · #9 09-16-2009, 10:27 PM

Thanks to everyone for the suggestions. I am going to get someone to check it with a set of gauges just to be sure.