What is the acceptable pressure level of charge on the low port of the A/C system? I am using one of those A/C pro trigger systems and am settling out at around 26-28 PSI on the trigger gauge. Per the instructions this should be in the 40-50 PSI range (between the red bars - based on the outside temperature). I don't have a proper set of gauges so kinda just working with what I have and adding r134 until the vent temperature dropped to a good level. Right now, with the car sitting in the garage, windows closed, air recirculating, 85-90 outside temp, I getting an air temp of around 42 degrees coming out of the vents. PSI is showing at around 26 PSI and stable. Driving around this goes UP to around 48 degrees so this is with air running over the condenser, not just been pulled in by the fan. When the re-circulation flap opens for a minute or two, the temp jumps up to around 60 and then goes back down to 42-45 or so once the flap closes again. If I remember correctly, the vent temp should be around 38-42 based on outside air coming in - I am showing 60 right now with the vent open. So the question is - should I keep adding more r134 and get the PSI up into the mid 30's or just say a thank you prayer to the Italian car God's that I have a 42-48 degree temp coming out and enjoy it? Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
You really need to buy a set of gauges, amazon or harbor freight they can be had for under $60. The low side only doesn't really tell you the story, you need to know the high side and fill it to what that chart says posted above
I do not think a chart should be used unless it is specific to a car set-up. Maybe the chart is a down dirty shortcut that scientifically works but that is not what I was taught. The correct way is to look at the WSM and there you will find the spec. 1st you suck out the system and place a vacuum on it and prove it holds proving no leaks and to suck out moisture that plugs the system through certain areas like the expansion valve. You use a 30lb can of freon on a scale and you fire in freon on the low side gage port watching the relative hi lo pressure to be in spec by the WSM. If the system calls for 2lbs you can read that off the scale. You do this so you do not overfill the system and wreck seals just like you don't want to overfill your oil. You can generally achieve about a 20 degree delta from ambient.
In finality of this - I emptied the rest of the small r134 can into the car, the low side gauge was jumping up to around 35psi, still far from the 40-50 range shown on the slider gauge. Temps using outside air around 43-44 degrees from an outside temp of 82 with low humidity. Will order gauges next year as obviously I have a leak and charge it up right next year... Calling it a day. Thanks guys.
