strange a/c problem w/ really high pressures | Ford Explorer Forums - Serious Explorations

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strange a/c problem w/ really high pressures

dynamite196

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Joined
September 22, 2006
Messages
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City, State
Glastonbury, Connecticut
Year, Model & Trim Level
97 Sport
This is my third go ahead with the a/c system on the explorer, the vehicle is a 97 sport, 4.0 ohv. To make a long story short the first time I refilled it was when I bought the vehicle, culprit turned out to be a bad low pressure switch, the second time I had to refill b/c of a blown compressor, and now the third time I'm refilling b/c of a bad compressor (again, that's what you get for buying used parts I guess). I followed glacier's write up, I was able to get about 27-28 mm Hg of vacuum and the vacuum held for 6 hours so I assumed no leaks and proceeded to start charging. I was able to get an entire can in through the high side without the motor running. Shut the high side off, turn the motor on, put the can upright in some warm water and open the low side. About a half can went in (so total maybe 20 oz in the system) before I started seeing the high side pressure shooting to the moon, it got up to 350 before I shut everything down. The system has evened out at about 110 psi on both the high and low side gauges. I replaced the orfice tube when I replaced the compressor so I'm pretty sure that's not the problem. Anyone have any ideas?
 






Did you flush the system out and replace the oriface tube? When a compressor goes, it can send metal into the system and plug the oriface tube.The oriface tube lives in the bottom line at the evaporater.
 






What was on the orifice tube? How is the fan clutch?

Fords and GMs too have a nasty habit of overheating the refrigerant system then chunking bits of teflon into the system as a compressor goes bye bye...If your orifice tube had any brown or black melted looking crap on it I would think the condensor has a restriction in it that did not flush out if it was flushed..

Now if the o-tube was clear and didn't have any melted crap on it, the next possibility for high pressures is that the airflow through the condensor and radiator is not adequate...

Does your fan clutch work? Is the cooling system working properly and clean? Do you feel air movement when running the engine when it is being charged and/or tested? If not or if not enough airflow, replace the fan clutch...You can test this step by running water around the condensor.. If your pressures drop, there is not sufficient airflow across the condensor and the likely culprit there is fan clutch or dirty cooling system...

BTW, the high side pressures especially when sitting still will be elevated due to lack of ram airflow into the condensor...The rule of thumb is to look for 2.2-2.7x ambient temp as a guide for the high side pressures...Here is Texas it is not uncommon to see 230-270 psi when the temp is hovering around 100 or so...Just an FYI...
 






Thanks for the help guys, I think I'm going to have to pull everything apart and do a thorough flush. I didn't see any chunks or gunk when I replaced the orfice tube last time so I assumed that wasn't a problem. While I'm at it I'll replace all the orings and accumulator too. Hopefully that'll solve the problem.
 






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