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5.7 liter engine. I have adequate pressure on my AC system according to both of the gauges I have tried. Compressor is engaging just fine, don't notice any strange noises or any other problems. Tried adding R134, it made the system a little cooler but not cold, and it rose the pressure out of the "safe" zone. Took the system back to normal pressure. Not sure what could be wrong at this point.
 

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your low side pressure should be 30-40 lbs the high side 200 and 300 if rear a/c is in it the low side should 35-45 lbs you might add more freon. let me know what happends now.
 

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Discussion Starter #3
I only have a gauge for the low side. I have to buy some more R134. I'll get back to you in a couple days. Thanks.
 

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Mine was acting the same way. I finally decided to just let some pressure out at the shraeder valve on the inlet side of the pump and refill it. Not much came out, so I fired up the truck, got the ac up to operating temps (where it was blowing luke-warm at best) and started filling with a new canister of R134. It took the whole can and half of another one to get it back to the correct pressure. I'm guessing I had a bubble or wasn't reading it right or some such. All I know is that it works again, blowing cold front and rear, even at 110 degrees ambient air temp.

Not sayin' what I did was right or safe...I really don't know. I do know I took my time, started with a new guage and took the steps on the can step by step AFTER I got the engine to op temp and the ac blowing as cold as it would get. Then my pressures read much lower than they did before and it took the recharge and works.
 

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to both of you pay the money and buy the r134a gauges there like $40 at harbor feight or find some online the gauges with save you in the long run. member low side 30-45 psi like 38 will be great, the high side 200-300 like 250 is great. under the hood somewhere there a sticker for r134a tahoes, yukons i think hold 2lbs and 8 oz of freon. maybe 2lbs 12 oz for the suburbans, yukon xl
 

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^ X2, buy the guages & wear eye protection in case a hose blows while you're charging.
 

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Yes to what was just said stay away from the AZ can with a gauge like it has something you can catch..low side depending on ambient should 35-40 tops make sure it does not creep up on you..high side after doing a few thousand cars 200-210 seems to produce the coolest vent temps.
When cking vent temps the fan should be on the setting _1 click_above the lowest in the middle vent with recirculate on.A great temp is below 50 f. But anything below 60 f. is considered okay.
Don't keep adding freon if you overfill the system you can cause major issues,you also might want to get someone to pull vacuum on it for an hour or so,really helps to have a dry system.
 
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