7
EXAMPLE: The low side pressure is 84 psi. The low side
temperature is 80°F. The outdoor temperature is 95°F.
The indoor temperature is 85°F. By referring to a pressure
temperature chart, you wil see that 84 psi equals a satu-
rated temperature of 50°F. The superheat is 80 - 50 =
30°F. The chart shows a superheat of 20°F is ideal for
these conditions. Since our superheat is 30 - 20 = 10°F
higher than ideal, charge must be added.
If the system is performing properly, reinstall the service
port caps and the valve bonnets. With the valve opened,
the valve bonnet is the primary seal against refrigerant
leaks. See the table below for the torque required for an
effective seal on the valve bonnet (1/6 turn past finger
tight).
Tubing Size
Torque (Foot-Pounds)
3/8
10
1/2, 5/8, 3/4
14
7/8. 1 1/8
16
After closing the valve bonnet, perform a final refrigerant
leak test on the valves and sweat connections. Return the
room thermostat to the desired settings.
TROUBLELSHOOTING
(QUALIFIED SERVICER ONLY)
When troubleshooting, the first step should always be to
check for clean coils, clean filter(s), and proper airflow.
Indoor airflow should be 350 to 450 CFM per ton of cooling,
based on the size of the outdoor unit. The most common
way of establishing indoor airflow is heating temperature
rise. Indoor airflow will then be (Heating output of equip-
ment) / (1.1 x temp. rise). In other cases, measurement of
external static pressure is helpful. For details, see the
Installation Manual for your indoor equipment.
If further information is needed, see the Remote Heat
Pump Service Manual.
Defrost System
GENERAL
Two types of defrost controls are used. To determine
which is on your unit, see the “Specification Sheet” shipped
with the unit.
Test
Terminals
T1=30
Minutes
T2=60
Minutes
T3=90
Minutes
Figure 5
TIME AND TEMPERATURE DEFROST CONTROL
OPERATION:Defrosting of the outdoor coil is determined
by both coil temperature and compressor run time. The
compressor run time is factory set at 90 minutes, and is
field adjustable to 30 or 60 minutes. Adjust only as required
by high outdoor humidity or other adverse conditions. If
adjustment of the run time appears advisable:
WARNING
To avoid electrical shock or death,
disconnect the power before changing the
defrost time cycle.
1. Move the control wire pin from T3 (90 minutes) to T2
(60 minutes), or T1 (30 minutes).
2. Reconnect the electrical power.
The maximum defrost time is 10 minutes. Most defrost
cycles are shorter.
