24
IM 725 (1-02)
Hazardous Voltage!
Disconnect all electric power including remote disconnects
before servicing. Failure to disconnect power before servicing
can cause severe personal injury or death.
Sight Glass
TXV (Thermal Expansion Valve)
Insulate Bulb
(Reacts To
Refrigerant
Temperature and
Not Ambient)
Insulate The
Suction Line Piping
(Minimum Heat
Pickup)
Return (Suction Line)
Supply (Liquid Line)
Figure 77 - Insulate Bulb and Suction Line Piping
Figure 78- Typical Split System Evacuation/Charging Set-up
Suction Line Service Valve
Liquid Line Service Valve
Outdoor Fan
Compressor
Gauge Bar Hoses
Vacuum Pump
Strainer
Drier
TXV
Indoor Fans
Charging
Cylinder
Indoor Coil
Outdoor Coil
Low Pressure
Gauge
Outdoor Condensing Unit
Unit Ventilator
High Pressure
Gauge
Figure 79 - Typical Unit Ventilator/Condensing Unit Wiring Diagram
Compressor
Compressor
Contactor
Capacitor
Head
Pressure
Controller
(Optional)
Fan
Motor
High
Pressure
Switch
Low
Pressure
Switch
TDR = Time Delay Relay
TB = Terminal Block
T4
2
3
1
Rec3
Line Voltage
Factory Wired
Field Wired (By Others)
TDR or TB
Low Ambient
Temp. Switch
T
1
T
2
L
2
L
1
L
2
L
1
24V
24V
Checking System Charge
The system charge should be checked under design conditions [95
°
F
outside air, 80
°
F/67
°
F (DB/WB) indoor air]. Refer to condensing unit
manufacturer's guidelines.
Before adjusting refrigerant charge, verify that the unit ventilator is
operating at normal design cfm. Nominal cfm is determined with a dry
coil, and cfm will be reduced during air conditioning operation with
a wet coil. Filters and coil must be clean and fan speed set at high.
temperature to obtain subcooling.
Determining Subcooling
To determine correct subcooling:
1. Measure outdoor ambient. It must be between 65
°
F and 105
°
F.
2. Measure liquid line temperature 6 inches from the TXV inlet.
3. Measure liquid line pressure near the TXV.
4. Determine saturated liquid temperature from saturated temperature
pressure chart (table 18).
5. Subtract measured liquid line temperature from saturated liquid
temperature to obtain subcooling.
6. Adjust charge per condensing unit manufacturer recommendation
to obtain 9 - 12
°
F subcooling.
(By Others)
(By Others)
Note:
Table 17 piping dimensions are for systems with up to 30 ft. (9.14 m) vertical
separation and up to 100 ft (30.47 m) horizontal separation from the outdoor
condensing unit.
Table 17 - Dimensions, DX Tubing inches (mm)
Models AVS, AVV,
AVB, AVR
Suction Line O.D.
Liquid Line O.D.
S07
3/4" (19mm)
1/4" (6mm)
S10
3/4" (19mm)
1/4" (6mm)
S13
7/8" (22mm)
3/8" (10mm)
S15
7/8" (22mm)
3/8" (10mm)
Typical Condensing Unit
Typical Unit Ventilator Interface
WARNING
!