There are several ways to determine if your air
conditioner is low on refrigerant.
Poor cooling. If your air conditioner isn't putting out
much cold air, it could be low on refrigerant. But an A/C system
can still produce cool air even if it's lost up to 50% of its
original charge of refrigerant. Even so, output will be reduced.
If the system is working properly, it should blow air that is
approximately 50 degrees cooler than the ambient air temperature.
Poor cooling, however, doesn't necessarily mean the refrigerant
is low. You might have another kind of problem. So to determine
the cause, the system should be diagnosed by a skilled professional
who understands air conditioning.
If your A/C system has a "sight glass" (a small
round glass window usually located on or near the receiver/drier
or accumulator), you can "see" inside the system. Refrigerant
is clear so it's hard to tell if the system is full or empty.
If the glass looks clear and there is no cold air output,
the system has lost its charge of refrigerant through a leak somewhere
in the system. If you see bubbles or foam in the sight glass,
it means the system is low on refrigerant and needs to be recharged.
The most accurate means of determining the refrigerant level
in your A/C system is with a set of A/C gauges. The gauges will
show how much pressure is in the high and low sides of the system.
The pressure specs vary from application to application, but
generally speaking a high side reading of less than 160 lbs. at
80 degrees F, and/or a low side reading of less than 16 to 22
lbs. at 80 degrees F indicate a need for additional refrigerant.
If you see oily streaks radiating outward around the compressor
shaft seal, or wet oily areas around hose connections, it means
refrigerant is leaking from your system. This too, may indicate
a need for additional refrigerant to replace that which has been
Most A/C systems leak a little refrigerant over time. Newer
systems are tighter and leak less than older ones, which may lose
up to several ounces of refrigerant a year. After five or six
years of service, therefore, it's not unusual for the system to
need some additional refrigerant.
If your A/C system can't hold a charge from one season until
the next, it has a major leak that should be pinpointed and repaired.
The type of refrigerant (R12) used in all vehicles built prior
to 1993 causes damage to the Earth's protective ozone layer.
So leaks should be repaired to prevent the loss of refrigerant.
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