114
Chapter 6
III.
Starting a System with Liquid
Refrigerant in the
Compressor
When most air conditioning and commercial sys-
tems are started up for the first time each season, a
large part of the system refrigerant charge is in the
compressor. If there is no crankcase heater or the
heat is not operating properly and the unit must be
started at the time of the service, then follow these
guidelines:
•
DO NOT attempt to heat the crankcase by
applying a flame to the compressor. Not only is
this process slow and likely to be ineffective, it
may damage electrical wires, paint, and the oil.
•
If there is no evidence of a compressor electrical
problem (for example, tripped breaker or
blown fuse, or reports of such), then “jog” the
compressor. To “jog” the compressor apply
power for one to two seconds, then wait 1 to 2
minutes. After 3 or 4 jogs, apply power contin-
uously.
WARNING!
Jogging a compressor that has
an electrical problem can increase the likeli-
hood of terminal venting. To reduce the risk of
serious burns or death from terminal venting
with ignition, you must FIRST check for a
ground fault whenever you suspect an electri-
cal problem. See “Identifying Compressor
Electrical Problems” on page 47 for addi-
tional information.
Figure 6-8.
Wiring diagram for PSC compressor with run capacitance off-cycle heat.
Internal
Thermal Protector
(optional)
External
Thermal Protector
Motor
Star
t
Winding
Main
Winding
Bleeder
Resistor
Run Capacitor
Single Can
(Split Capacitor Optional)
Bleeder
Resistor
Single Pole Contactor
or On - Off Switch
Temperature Control
(Room Air Conditioner)
Single Phase - PSC Type
Single Phase - CSR Type
Potential Relay
Line 1
Relay - Potential
Line 2
Ground
Start
Capacitor
A B
C
R
L
2
T
2
5
2
1
Hi
Side
Fan
S
C
L
1
Compressor -
Unit
Ground