Just
because there is some pressure in the A/C system does not mean that it has
enough refrigerant or that there is anywhere near enough to even consider
topping it off, even for test purposes.
Remember,
pressure gauge readings will not tell you how much refrigerant is in the
system. Now, when looking at static pressures, the only thing static pressures
could tell you is that there is ‘some’ refrigerant in the system.
But in order for that to be true, the pressures would have to be pretty close
the ambient air temperature in degrees Fahrenheit.
One
of the most confusing parts of auto A/C service is when a service technician
sees some pressure on the gauges and thinks that there really is some refrigerant
in the system. He proceeds to add some refrigerant for test purposes and
take the pressure gauge readings with the system operating. At that point,
the diagnosis of the A/C system has become very complicated. That’s
because the service technician has absolutely no idea of how much refrigerant
was in the system when he started and now that he’s added enough to
get the compressor to engage, the pressure gauge readings will be everything
but accurate.
Understand
that in almost every case, if the static pressure gauge readings start out
below 50 psi, the system should be considered empty. In fact, if the static
pressure gauge readings do not come close to reflecting the ambient air
temperature in degrees F, you should consider the system as being empty.
Adding refrigerant and running the system will get everything except the
correct pressure gauge readings. In most cases, a system that is that low
will contain some amount of air. With air in the A/C system, pressures will
tend to be higher than normal. WIth the high pressures, the service technician
is left doing and A/C diagnosis and chasing problems that are just not there.
Whenever
static pressures are lower than the ambient air temperature in degrees F,
you should always start by recovering any remaining refrigerant, pull deep
vacuum for at least 1/2 hour and then recharge the A/C system with the full
factory specified amount of refrigerant. That is the only method that will
allow you to properly test the A/C system’s performance and you will
know exactly how much refrigerant is in the sysetm. |
This
was probably one of the best books on recharging air conditioning that I
have seen...
