Just quickly, pressure readings do not tell you charge
level, but I agree throwing in one can like that --if you
know for sure low can fix it. If it is not low you can
overcharge , = disaster . The only way to correctly charge
is by weight of refrigerant and a scale -which they do in
an empty system or first pull out what is in there with
suction AC machine ( a law now) . Excess liquid
refrigerant is kept in the car receiver / dryer tank , by
It is like a propane tank .
Pressure is the same almost empty or full . Pressure is
Set only by temp of propane ,or refrigerant not by how
much is in tank .. for things that are liquid at room temp
under pressure , but change to gas if pressure drops .
Why gas comes out in your grill , not liquid . And flame
stays about the same size ( same pressure) as the liquid
tank empties on a hand held propane torch . And gets
cold. Straight compressed gas ( oxygen) non liquified yes
pressure tells you % full in cu ft .
Somewhere in FSM is weight in
oz of new charge .. about 2 cans + usually. By way of
understanding , not critique .
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Go to Walmart*,
there you will find a 134-A refill kit.
It consists of
a can of 134*A, a gauge, hose and handle.
Hook it up to
your system, Will only attach to one connector.
directions (Nobody will see you doing it)
What you want to do is watch the gauge and see what
the pressure is while it's running.
If it's low,
pull the trigger and add Freon until it gets the
pressure up to the range it wants.
The gauge has
the ranges marked on it, so it's easy.
but the rig in you tool box for future use, you can
add more bottles when you need them, I get them on
sale @ $3.85 or less @ Atwoods.
If you have a 2
gauge pro system, look for the pressure to be 1/2
ambient air temp on the low side and double or more
on the high side. Some charts I just looked at are
showing pressure to be triple ambient air temp.
And of course you add Freon thru the gauges.