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Old 09-24-2011, 05:26 PM   #1
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A/C pressure and quantity

Hey guys, this is my first post . I just bought a 1991 Wrangler this week and it came with factory A/C. It works and blows kinda cold but not where I think it should be. The sticker is missing from under the hood with the quantity of R12 to charge the system with. I have searched everywhere and have found numbers from 2.38 to 3 LBS. Any body have a the same set up with a 2.5L engine that could tell me the charge spec? I evacuated the system last night and pulled 1.25LBS out and recharged it with 2.25 based on what I have found so far but I'm still uncertain thats correct. 2.25 LBS gives me about 170 psi high side at about 75 degrees last night so I think I'm close. My other problem is that the low side is only 10 psi no mater have much I add or subtract, I tried 1.25 lbs up to 3 lbs and suction stays at 10 psi. bringing the engine above idle brings the suction psi down to about 5 psi. I'm a mechanic but a aircraft mechanic so my troubleshooting skills with freon is very limited. I just know enought to service the system and know when somthing just isnt right. Any help would really be a appreciated.

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Old 09-24-2011, 07:34 PM   #2
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I was having that problem...not cold enough....turns out there's a 2 piece one way valve in the end of the hose that attaches to the back side (evap. side) of the accumulator/drier...one part of that little tiny sucker was sticking....took it out and used very fine emory paper on it and the tube it rides in, swabbed it with refrigerant oil and now i'm blowing snow balls.....careful not to damage the o-rings on the 2 pieces and above all remember which way they come out.....BTW, mines a 91 too.....
and mine took exactly 2.75 lbs. plus a 2 oz. oil charge....
BTW, i put 134 in mine and no problems to date....just had to buy the kit that screws onto the inlet connectors to accept the 134 filler hose.....

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Old 09-24-2011, 07:50 PM   #3
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forgot to add that my high side is 235 psi and lo side is 38 psi....i'm getting 39 degree air from the vents when ambient air is 90 degrees
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Old 09-24-2011, 10:04 PM   #4
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Awsome, I will try it. Thanks
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Old 09-25-2011, 01:06 AM   #5
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I did some more research and found that that valve is just there as part of the install process and is not needed. The o-ring was torn. I removed it and charged it with 2.75 LBS and it blows 45 degree air. The pressures are still low at 12 low side and 165 high side. I think the compressor is just getting weak.
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Old 09-25-2011, 08:36 AM   #6
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or the expansion valve could be bad....it can cause low hi&low side pressures.......
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Old 09-25-2011, 08:38 AM   #7
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If the expansion valve is bad it can cause both the high and low pressures to be to low. That will be the case if it's stuck closed or partially closed....they're only 25.00...

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