GVZC20 Service Manual
SERVICING
22
gauge (low side) has dropped to approximately 29
inches of vacuum, open the valve to the vacuum micron
gauge. See that the vacuum pump will blank-o to a
maximum of 500 microns. A vacuum pump can only
produce a good vacuum if its oil is non-contaminated.
LOW SIDE
GAUGE
AND VALVE
HIGH SIDE
GAUGE
AND VALVE
TO
UNIT SERVICE
VALVE PORTS
VACUUM PUMP
VACUUM PUMP
ADAPTER
800 PSI
RATED
HOSES
CHARGING
CYLINDER
AND SCALE
EVACUATION
3. If the vacuum pump is working properly, close the valve
to the micron gauge and open the high and low side
valves to the vacuum manifold set. With the valve on
the charging cylinder closed, open the manifold valve to
the cylinder.
4. Evacuate the system to at least 29 inches gauge before
opening valve to micron gauge.
5. Continue to evacuate to a maximum of 500 microns.
Close valve to vacuum pump and watch rate of rise. If
vacuum does not rise above 500 microns in three to ve
minutes, system can be considered properly evacuated.
6. If micron gauge continues to rise and levels o at about
2000 microns, moisture and non-condensables are still
present. If gauge continues to rise a leak is present.
Repair and re-evacuate.
7. Close valve to micron gauge and vacuum pump. Shut
o pump and prepare to charge.
Charge the system with the exact amount of refrigerant.
See the Installation Manual for the correct refrigerant
charge.
An inaccurately charged system will cause future problems.
1. When using an ambient compensated calibrated
charging cylinder, allow liquid refrigerant only to enter
the high side.
2. Once the system stops taking refrigerant, close the valve
on the high side of the charging manifold.
3. Start the system and charge the balance of the refriger-
ant through the low side.
NOTE: R410A should be drawn out of the storage container
or drum in liquid form due to its fractionation properties, but
should be “Flashed” to its gas state before entering the sys-
tem. There are commercially available restriction devices
that t into the system charging hose set to accomplish this.
DO NOT charge liquid R410A into the compressor.
4. With the system still running, close the valve on the
charging cylinder. At this time, you may still have some
liquid refrigerant in the charging cylinder hose and will
denitely have liquid in the liquid hose. Reseat the liquid
line core. Slowly open the high side manifold valve and
transfer the liquid refrigerant from the liquid line hose
and charging cylinder hose into the suction service valve
port. CAREFUL: Watch so that liquid refrigerant does
not enter the compressor.
FINAL CHARGE ADJUSTMENT
The outdoor temperature must be 65°F to 105°F. If out-
door ambient temperature is out of range, charge dened
amount and don’t adjust subcooling. Set the room thermo-
stat to CHARGE mode.
After system has stabilized per startup instructions, check
subcooling as detailed in the following section.
In the event of system overcharge or undercharge, refrig-
erant in the system must be adjusted to the appropriate
subcooling and superheat as specied in the following
sections. Refrigerant amount should be adjusted within
+/- 0.5 lb. if the outdoor ambient temperature is greater than
65°F and less than 105°F. Manufacturer recommends that
the system should be evacuated and should be charged
the initial refrigerant for given line length when the ambient
temperature is less than 65°F and more than 105°F. Refer
to the Installation Manual to calculate refrigerant amount.