An Inaccurately Charged System: Problems; S-104 Checking Compressor Efficiency - Goodman GSH Series Service Instructions Manual

SERVICING
CAUTION
Use refrigerant certified to AHRI standards. Used
refrigerant may cause compressor damage and will
void the warranty. Most portable machines cannot
clean used refrigerant to meet AHRI standards.
CAUTION
Operating the compressor with the suction valve
closed will void the warranty and cause serious
compressor damage.
Charge the system with the exact amount of refrigerant.
Refer to the specification section or check the unit name-
plates for the correct refrigerant charge.
An inaccurately charged system will cause future prob-
lems.
1. When using an ambient compensated calibrated charg-
ing cylinder, allow liquid refrigerant only to enter the high
side.
2. After the system will take all it will take, close the valve
on the high side of the charging manifold.
3. Start the system and charge the balance of the refriger-
ant through the low side. DO NOT charge in a liquid
form.
4. With the system still running, close the valve on the charg-
ing cylinder. At this time, you may still have some liquid
refrigerant in the charging cylinder hose and will definitely
have liquid in the liquid hose. Reseat the liquid line core.
Slowly open the high side manifold valve and transfer the
liquid refrigerant from the liquid line hose and charging
cylinder hose into the suction service valve port. CARE-
FUL: Watch so that liquid refrigerant does not enter the
compressor.
5. With the system still running, reseat the suction valve
core, remove hose and reinstall both valve core caps.
6. Check system for leaks.
NOTE: This charging procedure can only be done in the
cooling mode of operation. (Early production "a" models
only.) All models with compressor process tube access
valve can be processed in heating cycle if this valve is
used.
When charging a remote condensing unit with a non-match-
ing evaporator coil, or a system where the charge quantity is
unknown, alternate charging methods must be used. These
systems must be charged according to subcooling or super-
heat.
52
SYSTEM SUPERHEAT
Ambient Condenser
Inlet Temp.
(°F Drybulb)
115
100
95
90
85
80
75
70
65
60
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.
Return Air Temperature
(°F Drybulb)
65 70 75 80
5
5 5
7 12
5 10 17
5 12 21
5 10 17 25
5 14 20 28
13 19 26 32
17 25 30 33
Table 7
85
3
5
5
18
20
26
29
32
35
37