CSCF R-22 Service Manual

SERVICING
57
65 70 75 80 85
115
3
100
55
95
555
90
71218
85
5101720
80
5122126
75
5 10172529
70
5 14202832
65
13 19 26 32 35
60
17 25 30 33 37
Return Air Temperature
(°F Drybulb)
SYSTEM SUPERHEAT
Ambient Condenser
Inlet Temp.
(°F Drybulb)
Table 7
Coils having flow control restrictors should be charged to
match the System Superheat chart above. Coils with ther-
mostatic expansion valves (TXV's) should be charged by sub-
cooling. See "Checking Subcooling and Superheat" sec-
tions in this manual.
Due to their design, Scroll compressors are inherently more
tolerant of liquid refrigerant.
NOTE: Even though the compressor section of a Scroll com-
pressor is more tolerant of liquid refrigerant, continued flood-
back or flooded start conditions may wash oil from the bear-
ing surfaces causing premature bearing failure.
If a restriction is located, replace the restricted part, replace
drier, evacuate and recharge.
S-104 CHECKING COMPRESSOR EFFICIENCY
The reason for compressor inefficiency is broken or dam-
aged suction and/or discharge valves, or scroll flanks on Scroll
compressors, reducing the ability of the compressor to pump
refrigerant vapor.
The condition of the valves or scroll flanks is checked in the
following manner.
1. Attach gauges to the high and low side of the system.
2. Start the system and run a "Cooling Performance Test.
If the test shows:
a. Below normal high side pressure.
b. Above normal low side pressure.
c. Low temperature difference across coil.
d. Low amp draw at compressor.
and the charge is correct. The compressor is faulty - replace
the compressor. NOTE: THIS TEST CANNOT BE DONE IN
THE HEATING MODE
Verification of proper rotation of Scroll Compressors is made
as follows.
NOTE: The compressor may run backwards (noisy opera-
tion) for 1 or 2 seconds at shutdown. This is normal and
does not harm the compressor.
1. Install gauges and verify that the suction pressure drops
while the discharge pressure increases.
2. Listen for normal compressor sound levels. Reverse rota-
tion results in elevated or unusual sound levels.
3. Reverse rotation will result in substantially reduced amp
draw from tabulated values.
To correct improper rotation, switch any two power supply
leads at the outdoor unit contactor.
The 3 phase Scroll Compressors are direction of rotation sen-
sitive. They will rotate in either direction depending on the
phasing of the power. There is no negative impact on durabil-
ity caused by operating 3 phase compressors in reversed
rotation. The compressors internal protector will trip, de-en-
ergizing the compressor. Continued operation of 3 phase scroll
compressors with the rotation reversed will contribute to com-
pressor failure. All 3 phase scroll compressors should be
checked for correct phase rotation.