Service manual

50
Installation and Service Manual
EVACUATION AND CHARGING
SYSTEM EVACUATION AND CHARGING / ALL REMOTE SYSTEMS
DISCHARGE, EVACUATION & RECHARGING PROCEDURES
System Evacuation and Charging
Self-Contained Units
If service work is done on the unit where the refrig-
eration system is opened for any reason, the system must
be evacuated BEFORE it is re-charged. Purging the
system is NOT acceptable. Evacuate system through
both high and low side service valves. Be certain both
valves are completely open when evacuating and drier
has been replaced.
Evacuate the system to approximately 200/250 mi-
crons. At this range, ther should be a holding test of five
minutes. You may expect a slight loss of vacuum as nor-
mal. A rapid rise to normal atmospheric pressure indi-
cates a system leak - while a slower rise to approximately
1500 microns indicates moisture still present in the sys-
tem. On a "wet" system, it will prove beneficial to use
heat lamps to warm the compressor dome and evapora-
tor surface during evacuation.
System Charging
Charging by sight glass, system pressures, amper-
age or temperature are not acceptable methods for
Servend equipment. To assure a properly charged unit
(after proper evacuation), the charge should be weighed
into the unit using an electronic charging scales or dial-
a-charge.
On air and water cooled self-contained units, the
charge should be introduced into the high side of the
system through the high side service valve.
CAUTION: All aspects of the Clean Air Act of July
1992, MUST be followed in recovery of system re-
frigerant.
All Remote Systems Discharge, Evacuation & Re-
charging Procedures
All field repairs to the sealed system must start with a total
discharge of the system following the requirements of the Clean
Air Act of July 1992.
Proper evacuation of the total system will require three (3)
point hook-up:
1. Receiver Inlet Service Valve - This evacuates the area
between the condenser check valve, through the liq-
uid line solenoid to the expansion valve.
NOTE: If the receiver valve stem is fully back seated, the
gage port is closed.
2. Suction Side at the Compressor or Low Side Service
Valve - This evacuates the suction side between the
compressor and solenoid valves.
3. Discharge Side at the Quick Connect Service Port -
This evacuates the high side between the compres-
sor and the head pressure control. The quick con-
nect service ports are equipped with valve cores.
Remove cores with a valve core extractor prior to
evacuation and charging.
4. Evacuate the system to 13 PSI (.90Bars). This will
open the low pressure cut-out, removing power from
the compressor pump down circuit. Place the toggle
switch in the on position. This opens the liquid line
solenoid permitting evacuation of the liquid line be-
tween the solenoid and the expansion valve(s).
5. Evacuate system to approximately 200/250 microns.
At this range, there should be a holding test of five (5)
minutes. You may expect a slight loss of vacuum as
normal. A rapid rise to normal atmospheric pressure
indicates a system leak - while a slower rise to ap-
proximately 1500 microns indicates moisture still
present in the system. On "wet" system, it will prove
beneficial to use heat lamps to warm the compressor
dome and evaporator surface during evacuation.
7. All refrigerant recharging must be weighed into the
sytem, utilizing an electronic charging scales. DO NOT
attempt to recharge the system by sight glass, sys-
tem pressures, amperage, frost line or sweat patterns.
*CAUTION: Before programming the electronic
scales to "dump" the charge, de-energize the pump-
down solenoid, close the shut-off valve on vacuum
pump and low side of the manifold set.