Page 15
2 – RFCIII Systems
The system should not be charged at ambients below
60
F (15
C). If charging below 60
F (15
C) is required,
the recommended method of charging is to weigh the
refrigerant into the unit according to the total amount
shown on the unit nameplate. For line sets varying from
20 feet , refer to table 8 for refrigerant charge adjustment.
If ambient temperature is above 60
F (15
C) use the
subcoooling method outlined below.
SUBCOOLING METHOD (RFCIII SYSTEMS)
(Ambient Temperature Above 60
F [16
C] )
1 – Connect gauge manifold. Connect an upright
R–22 drum to center port of gauge manifold.
2 – Operate indoor and outdoor units in cooling
mode. Allow outdoor unit to run until system
pressures stabilize.
3 – Make sure thermometer well is filled with
mineral oil before checking liquid line
temperature.
4 – Read liquid line pressure and convert to
condensing temperature using temperature/
pressure conversion chart.
Condensing temperature (read from gauges)
should be a few degrees warmer than the
liquid line temperature.
Outdoor
Unit
Indoor
Unit
65
F 75
F 85
F 95
F 105
F 115
F
CB19–51
HP23–510
HP23–141
HP23–211
HP23–261
HP23–410 (CAN) CB/CBH19–41
CB/CBH19–26
CB/CBH19–21
CB/CBH19–21
CB/CBH19–31
CB/CBH19–41
HP23–311
HP23–460
SUBCOOLING METHOD––RFCIII Systems*
5
13
12
12
11
11
5
13
12
12
10
10
4
13
11
10
7
8
1
12
9
8
6
7
0
6
7
6
4
5
0
4
5
4
2
2
*Approved matchups only
HP23–410
CB/CBH19–41
17
15
14
11
8
5
18
16
15
12
9
6
Condensing Temp
°
F Warmer
Than Liquid Line At Various
Ambients
5 – Place thermometer in well and read liquid line
temperature. Table 12 shows how much
warmer the condensing temperature should be.
Add refrigerant to make the liquid line
temperature cooler.
Recover refrigerant to make the liquid line
temperature warmer.
6 – When unit is properly charged liquid line
pressures should approximate table 11.
E – Oil Charge
Refer to table 5 on page 6.
V – MAINTENANCE
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
A – Outdoor Unit
1 – Clean and inspect outdoor coil. (Coil may be
flushed with a water hose).
2 – Visually inspect all connecting lines, joints and
coils for evidence of oil leaks.
IMPORTANT
If insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge checked.
B – Indoor Coil
1 – Clean coil if necessary.
2 – Check connecting lines and coil for evidence of
oil leaks.
3 – Check condensate line and clean if necessary.
C – Indoor Unit
1 – Clean or change filters.
2 – Adjust blower cooling speed. Static pressure
drop over coil should be checked to determine
correct blower CFM. Refer to Lennox
Engineering Handbook.
3 – Belt Drive Blowers - Check condition and
tension.
4 – Check all wiring for loose connections.
5 – Check for correct voltage at unit.
6 – Check amp–draw on blower motor.
Unit nameplate_________Actual_________.
