Ac not blowing cold

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josephmast94

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The air coming out of my main vents and rear vents is not as cold a it use to be. I am hearing what I believe the be the rear txv hissing as the compressor cycles on and off. I just got a set of manifold gauges from O'Riley's loaner tool program, here are my readings.
Ambient - 70°
Static system pressure - 84psi equalized
High side when compressor kicks on - 125psi
Low side when compressor kicks on - 30psi
High side when compressor is cycled off - 100psi
Low side when compressor is cycled off - 50psi

What is going on? Are those numbers within an acceptable range? Should I try adding refrigerant? I am considering pulling all the refrigerant out, vacuuming, and replacing the correct amount just to see what happens.
 

stamp11127

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High side pressure is low according to the chart in the sticky in the Heating / Cooling section. Make sure the condenser is clean and the cooling fan & fan clutch or electric fans are running correctly. Fan shroud should also be in place.
If you can recover and recharge the system that will make things easier to diagnose - that way you are starting within specification.
 

johnboneske

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Its all about outside temp to when charging don't forget. 30 psi low side if I remember correctly is proper charge at 60°. If it is hissing in the rear, it has a low charge. Probably will need 1 to 2 pounds to it right.
 

1955moose

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Yeah, looks like your low but not much. Probably popping in about 10-12 ounces should bring your numbers up. I buy mine in small 12 oz cans. Be sure to wear safety glasses, and wrap a rag around can of freon as you shake it and add it to system low side. Cans get mighty cold!. You might want to have a shop do a beeper test after to see if you have any small leaks. Hopefully it's not the rear. Their harder to get at, but are usually your trouble spot.

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GAINMOB

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Yulp... got his answer and gone with no feedback

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1955moose

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They seem to do that a lot around here. I think what it is, is the other websites are so dead, it takes a week or more, just to have a post answered. We're like the old Domino's Pizza delivery, 30 minutes or less!

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jflip

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2000 XLT 5.4- hissing noise located at rear left panel, seems to be coming from a small square metal box. I seem to hear the compressor turn on, then hissing, then the compressor cycles off, no hissing, and repeats over and over when I have my ac on.

I read that this may indicate low refrigerant, but any other insight?

FYI I have the crossover antifreeze spew happening on top of 1-4 coils/plugs/boots. I changed 1-4 plugs and cleaned the boots, and I believe bought time until the next fouling! Paid $1100 for all 8 plugs/coil/boots 8 years ago. Never again. Long term fix is to replace the intake manifold cover, right?
 

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