36
Service Procedures
Testing for Restrictions
(continued)
•
If temperature of condenser tubing is consistent
throughout, go to step 4.
•
If temperature of condenser tubing drops
suddenly at any point, tubing is restricted at
point of temperature drop (if restriction is severe,
frost may form at point of restriction and extend
down in direction of refrigerant flow is system).
Go to step 5.
3. Visually check system for kinks in refrigeration
line which is causing restriction. Correct kink
and repeat step 2.
4. Turn unit off and time how long it takes high and
low pressure gauges to equalize.
•
If pressure equalization takes longer than 10
minutes, a restriction exists in the capillary tube
or drier filter. Go to step 5.
•
If pressure equalization takes less than 10
minutes, system is not restricted. Check for
other possible causes of malfunction.
5. Recover refrigerant in sealed system’
NOTE:
Before opening any refrigeration system,
capture refrigerant in system for safe disposal.
6. Remove power from unit.
To reduce risk of personal
injury or property damage, take
necessary precautions against high temperatures
required for brazing.
7. Remove and replace restricted device.
8. Evacuate
sealed
system.
9. Charge system to specification.
NOTE:
Do not use captured or recycled refrigerant
in Viking units. Captured or recycled refrigerant
voids any Viking and /or compressor
manufacturer’s warranty
NOTE:
Charge system with exact amount of
refrigerant. See Technical Sheet or refer to unit
nameplate for correct refrigerant charge.
Inaccurately charged system will cause future
problems
Evacuation and Charging
To avoid risk of fire, sealed
refrigeration system must be air
free. To reduce risk of air
contamination, follow evacuation procedures exactly.
NOTE:
Before opening any refrigeration system,
EPA regulations require refrigerant in system to
be captured for safe disposal.
Proper evacuation of sealed refrigeration system is an
important service procedure. Usable life and
operational efficiency greatly depends upon low
completely air, moisture and other non-condensables
are evacuated from sealed system.
Air in sealed system causes high condensing
temperature and pressure, resulting in increased
power requirements and reduced performance.
Moisture in sealed system chemically reacts with
refrigerant and oil to form corrosive hydrofluoric and
hydrochloric acids. These acids attack motor
windings and parts, causing premature breakdown.
Before opening system, evaporator coil must be at
ambient temperature to minimize moisture infiltration
into system.
Evacuation
To evacuate sealed refrigeration system:
1. Connect vacuum pump. Vacuum tight manifold
set with tight vacuum hoses, thermocouple
vacuum gauge and charging cylinder as shown in
illustration. Evacuation should be done through
I.D. opening of tubes not through line piercing
valve.
