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A/C cycles every 3 seconds. Need help.

Dblbogey

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'97 XLT
This is my first post, so here goes... I noticed sometime back that my compressor was cycling more than usual, maybe once every 3-5 seconds, so I added a can of 134 freon. No change. I had the freon recovered and pulled the orifice tube. It was nasty with alot of grey, metallic goo on both ends of the tube. I then proceded to flush the evaportator and A/C hoses. I did not flush the condenser (I wish I did). I put in a new orifice tube, accumulator, oil, and recharged with the proper amount of freon (26 oz). Had the same result as before - excessive cycling of compressor. So now I think the compressor is bad and I buy a new one and put it in. Same results -click...click...click... I jumper the low pressure switch and the compressor now stays on. low pressure at 10 lbs and high pressure at 100 lbs. These pressures seem very low so I add one more can of freon. Now pressures are at 20 lbs and 120 lbs. Still low but I know there is enough freon in the system. This now sounds to me that the orifice tube is plugging again. Could this be anything other that a plugging issue? Thanks for any help.
Dblbogey (double bogey) '97 XLT SOHC
 
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96 Explorer XLT

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Do you have the same cycling with the heat on? Im in the same boat as you with a brand new AC system-including the compressor. Freon is fine. Cycles every 2-3 seconds and I know its not normal. Its noisey as well. My thoughts are I may have received a defective compressor-its still under warranty.
 
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shamaal

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Rapid cycling is evidence of low charge. Why charge is low - leak, compressor, clog is determined by troubleshooting.

@dblbogey - Metallic crap in orifice screen is not good. IMO problem points to a weak compressor, the orifice may also be clogged also. If the problem is just the orifice clogged - I would think that you would see a higher pressure differential. Another possibility is a leak big enough that the system can't build up presure. Something like that may be audible.

I didn't see any evacuation (vacuum) in your writeup, necessary to get the moisture out. Does it hold vacuum for 15 minutes; that would reduce the likliehood of a leak as the problem.

@96 Explorer - Noisy not good; is there sufficient oil in system? If compressor is bought as a component, they will usually wish to see evidence of accumulator and orifice replacement before honoring. Say yes, you did that, but you didn't keep the receipt, unless of course you really did. If warranty is from shop, bring vehicle back.
 
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bp1506

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same problem with mine cycles every 5- 10 seconds when in idle, i havent been able to notice if it does it while i am driving on the highway. But yeah usually cycling on and off means low charge.
 
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Dblbogey

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Shamaal,
I evacuated for at least 1 hour - vacuum held for 15+ minutes so I don't expect a leak. Compressor is brand new so I don't expect that to be bad. Is there any good method in determining a clog other than opening up the system?

96 Explorer XLT,
Haven't checked with the heat on yet. Will do next time I'm out.

I hope I don't have what's called "black death". A fair amount of junk came out of the evaporator when I flushed it. Like I said before, I did not flush the condenser, but wish I had. Could of had stuff in there that plugged off the orifice tube again.
 
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reserved50

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if everything else is fine I would expect 30 and 150ish psi, still kind of low now(needs more 1334a?)
 
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shamaal

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Holding a vacuum for 15 minutes pretty much reduces a leak as a problem. As I understand it black death is as a result of teflon seals breaking down, they're no longer used in compressors I'm told.
I still think that a clog in the system would cause a higher pressure differential than you are seeing, but I guess it's possible that the compressor's not running long enough to raise it.

Occasionally you can feel where the restriction is, warm on one side cold on the other. Seeing as the orifice is supposed to act like a calibrated restriction it's naturally cold at the junction anyway.

Generally speaking compressors on these systems are fairly reliable assuming that they have sufficient oil in the system. For the '97 Explorer that should be 9 oz according to Haynes.

Sounds like you have another flush in your future.
 
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rmcknight

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i also have this, but i wasn’t concerned about it until reading all the others! hmm i know nothing about A/C except that it harms our ozone layer!!!!! (not good for polar bears!, but good for cockroaches!)

I have been running with this for 2 years with no difference (10 second cycle!), I think it may be computer related or sensor related as the pressure seems fine to the touch in the pipes?
 
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adam4584

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was the vacuum steady or was it fluctuating or was it steadily falling?
 
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ma96782

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FWIW:

Book pressures for the '97 Explorer....Haynes Automotive Heating and A/C:

automatic systems:
low; 20-50
high; 160-250

manual systems:
low; 22-50
high; 160-250

*at sea level and ambient air temp of 80 degrees F
______________________

oil capacity: 9oz

______________________

refrigerant: 1.38 pounds

_______________________________________________________________

You sound like you know your way around......so as a refresher....... how about fan clutch operation? Fan placed in front of condenser? Adjustments for altitude? Adjustments for ambient air temps?

I don't know where you're located......far northern part of USA? How about waiting to test, when the weather warms up??

Aloha, Mark
 
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Dblbogey

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Thanks for all the replies. I think I'm going to wait for the weather to warm a bit before diagnosing any more. I did this work while it was pretty cool (~50F), so the system may be functioning more normal than I think.
ma96782 shows that the Haynes manual pressures are performed at 80F and at sea level. Well, I'm at sea level (~80 miles south of Houston) so now I just need it to warm up a little.

Dblbogey
 
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