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A/C charging question

james t

Elite Explorer
Moderator Emeritus
January 27, 2002
Reaction score
City, State
Texarkana AR/TX
Year, Model & Trim Level
94 SAS sport
96 model 5 liter, 134a

I have the gauge on the low side, ran air for 3 minutes on max/high and im showing 35psi. The gauge shows this to be right in the middle of "filled" 25-45 being normal. My air never blows cold anymore... just kinda "cool". Should i go ahead and charge it to the full 45psi?

From what i understand, the pressure readings are not accurate do to ambient temperature. In other words, its 100 degrees right now and HAWT outside. Could this mean that my 35lb. reading is really a little low? In other words.... if it were 70 degrees outside instead of 100+ would my reading be closer to 25lbs?

Update- i went ahead and charged it to the full 45lbs and it blows ice cold now. I guess my theory was right- the 35lb i was reading on the gauge was not really 35lbs because its 104 and 91% humidity outside.

I guess. Maybe. Hell, i dunno. Its at 45 now and its dam cold. Thats all i care about. :p

The system pressure on an operating system is not adjusted based on ambient. A single side reading does not always give you all the data. The cheapie gauges sem to be often off quite a bit too. 35 PSI low side in a perfect system SHOULD be cold air. Who knows, important thing is you fixed it. For whatever reason you were not getting enough refrigerant in the evaporator to fully utilize it's ability to absorb heat. and are now.

Ah, ok. Well i assume its just a cheapo gauge thats not calibrated very well. Either way, it works now. My guesses were just that mainly because i know jack squat about AC. :p