507043-01
Issue 1222
Page 6 of 8
Cooling Cycle Charge Adjustm ent Procedure
Units with Indoor Pistons
Units installed with indoor pistons require charging with
the superheat m ethod.
The following procedure is valid when indoor airflow is
within ± 20% of its rated CFM.
1.
Operate unit a m inim um of 10 m inutes before
checking charge.
2.
Measure suction pressure by attaching a gage to
suction valve service port. Determ ine saturation
tem p from T/P chart.
3.
Measure suction tem perature by attaching an
accurate therm istor type or electronic therm om eter
to suction line at service valve.
4.
Calculate superheat (m easured tem p. — saturation
tem p.).
5.
Measure outdoor air dry-bulb tem perature with
therm om eter.
6.
Measure indoor air (entering indoor coil) wet-bulb
tem perature with a sling psychrom eter.
7.
Com pare superheat reading at service valve with the
chart located on control box cover.
8.
If unit has a higher suction line tem perature than
charted tem perature, add refrigerant until charted
tem perature is reached.
9. If unit has a lower suction line tem perature than
charted tem perature, reclaim refrigerant until charted
tem perature is reached.
10. Rem ove charge if superheat is low and add charge
if superheat is high.
Units w ith Indoor TXV
Units installed with cooling m ode TXV require charging
with the subcooling m ethod.
1.
Operate unit a m inim um of 10 m inutes before
checking charge.
2.
Measure liquid service valve pressure by attaching
an accurate gage to service port. Determ ine
saturation tem p. from T/P chart.
3.
Measure liquid line tem perature by attaching an
accurate therm istor type or electronic therm om eter
to liquid line near outdoor coil.
4.
Calculate subcooling (saturation tem p.— m easured
tem p.) and com pare to table on back of control box
cover.
5.
Add refrigerant if subcooling is lower than range
shown in table. Recover refrigerant to decrease
subcooling.
6.
If am bient tem p. is lower than 65
/
F, weigh
refrigerant according to the nam e plate data.
NOTE: If a TXV is installed on indoor unit, a hard start
kit w ill be required on all models w ith
reciprocating compressors. Refer to the
specification sheet for details. Hard start kits
are also recom m ended for areas w ith utility
pow er low er than 208 Vac.
SYSTEM OPERATION
The outdoor unit and indoor blower cycle on dem and
from the room therm ostat. W hen the therm ostat blower
switch is in the ON position, the indoor blower operates
continuously.
Filter Drier
The outdoor unit is equipped with a filter drier. If
replacem ent is necessary, order new dryer according to the
service parts m anual.
