37
Service Procedures
Evacuation
(continued)
2. Connect low side line to compressor process
tube.
3. Connect high side line to drier / process tube.
4. Evacuate both simultaneously. With valve “C”
and “F” closed, open all other valves and start
vacuum pump.
5. After compound gauge (low side) drops to
approximately 29 inches gauge, open valve “C”
to vacuum thermocouple gauge and take micron
reading.
6. Continue evacuating system until vacuum gauge
registers 600 microns.
7. At 600 microns, close valve “A” to vacuum
pump and allow micron reading in system to
balance. Micron level will rise.
•
If in 2 minutes, micron level stabilizes at 1000
microns or below, system is ready to be charged.
•
If micron level rises above 1000 microns and
stabilizes, open valve “A” and continue
evacuating.
•
If micron reading rises rapidly and does not
stabilize, a leak still exists in system.
Close valve “A” to vacuum pump and valve “C” to
vacuum gauge. Invert charging cylinder and open
charging cylinder valve “F” to add partial charge for
leak checking. With leak detector, check manifold
connections and system for leaks. After locating leak,
capture refrigerant, repair leak, and begin
at step
1.
Charging
NOTE:
Do not use captured or recycled refrigerant
in Viking units. Captured or recycled
refrigerant void any warranty.
NOTE:
Charge system with exact amount of
refrigerant. See Technical Sheet or refer to
unit serial plate for correct refrigerant
charge. Inaccurately charged system will
cause future problems.
To charge system:
1. Close valves “A” to vacuum pump and “C” to
vacuum gauge and “E” to low side manifold
gauge.
2. Set scale on dial-a-charge cylinder for
corresponding HFC134a pressure reading.
3. Open valve “F” to charging cylinder and let
exact amount of refrigerant flow from cylinder
into system. Close valve.
Low side gauge pressure should rise shortly after
opening charging cylinder valve as system pressure
equalized through capillary tube.
If pressure does not equalize, a restriction typically
exists at capillary/drier braze joint.
4. If pressure equalizes, open valve “E” to low side
manifold gauge and pinch off high side drier
process tube.
5. Start compressor and draw remaining refrigerant
From charging hoses and manifold into
compressor through compressor process tube.
6. To check high side, pinch off drier process tube.
Close valve “D” to high side gauge. If high side
Pressure rises, repeat high side pinch off and
open valve ”D”. Repeat until side pinch off does
not leak.
7. Pinch off compressor process tube and remove
charging hose. Braze stub closed while
compressor is operating.
8. Disconnect power. Remove charging hose and
braze high side drier process tube closed.
9. Recheck for refrigerant leaks.
Refrigerant Charge
Refrigerant charge in all capillary tube system is
critical and exact amount is required for proper
performance. Factory charges are shown on serial
plate. Do not use refrigerant other than shown on
serial plate.
HFC134a Service Information
To minimize risk of contamination which can cause
property damage, exercise extreme care when
servicing R134a sealed systems
•
No trace of other refrigerant
is allowed in HFC134a
systems. Chlorinated molecules in other
refrigerants such as CFC12, etc. will lead to
capillary tube plugging.
•
Ester oil is used in HFC134a systems. Do not
use mineral oil. HFC134a and mineral oils
cannot be mixed. If mineral oils were used in
HFC134a systems, lubricant would not return to
compressor and would cause early compressor
failure. If significant amount of oil has been lost
from compressor, replace oil rather than adding
oil.
•
Ester oils used in HFC134a systems are so
hydroscopic that by the time an adequate system
Performance is detected, oil will be saturated
with moisture.
•
CFC12 has much higher tolerance to system
processing materials, such as drawing
compounds, rust inhibitors, and cleaning
compounds, than HFC134a. Such materials are
not soluble in HFC134a systems. If materials
were to be washed from system surfaces be ester
oils, they could accumulate and eventually plug
capillary tube
