Appeal 2007-1444
Application 10/732,497
operation, the system provides two levels of indication of the degree of a
low charge condition. (Scoccia, col. 2, ll. 15-20).
2. Scoccia teaches measuring refrigerant pressure when the compressor is
not currently on and determining if that pressure is above PCAL(AMB)
(Scoccia, col. 4, ll. 61-67). Scoccia defines PCAL(AMB) as a
predetermined value that represents the lowest acceptable refrigerant
charge for the existing (measured) ambient temperature (AMB).
PCAL(AMB) values are based on the refrigerant saturation pressure for
the refrigerant at the given ambient temperature. Those values are
established such that a system with sufficient refrigerant charge will have
a pressure higher than the PCAL(AMB). (Scoccia, col. 4, l. 67 – col. 5, l.
8).
3. Scoccia recognizes that the refrigerant pressure becomes equalized only
when compressor non-operation occurs for at least a predetermined
period of time. The disclosed system senses and indicates a low charge
condition only if the compressor has been in the non-operating condition
for a sufficient time for the system to be equalized, or stable, with
compressor non-operation and the refrigerant pressure is still very low.
(Scoccia, col. 2, ll. 36-47).
4. Scoccia does not teach determining an amount of refrigerant charge loss
from the system based upon the difference between the expected pressure
and the determined equilibrium pressure. The disclosure of Scoccia is
limited to determining that the level is low based on comparison of
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