Specifications

42
Evacuation
WARNING
TO PREVENT SEVERE BURNS. DO NOT ALLOW THE
SLUDGE OR OIL TO CONTACT THE SKIN.
IMPORTANT NOTE: Effective July 1,1992. Before opening any
refrigerant system it is the responsibility of the service technician
to capture the refrigerant for safe disposal.
This is the most important part of the entire service procedure.
The life and efficiency of the equipment is dependent upon the
thoroughness exercised by the serviceman when evacuating
air (non-condensables) and moisture from the system.
Air in the system causes high condensing temperature and
pressure, resulting in increased power input and reduced per-
formance.
Moisture chemically reacts with the refrigerant and oil to form
corrosive hydrofluoric and hydrochloric acids. These attack
motor windings and parts, causing breakdown.
The equipment required to thoroughly evacuate the system is
a high vacuum pump, capable of producing a vacuum equiva-
lent to 50 microns, and a thermocouple vacuum gauge to give
a true reading of the vacuum in the system.
NOTE: Never use the system compressor as a vacuum pump
or run when under a high vacuum. Motor damage could occur.
1. Connect the vacuum pump, vacuum tight manifold set with
high vacuum hoses, thermocouple vacuum gauge and charg-
ing cylinder.
2. Connect the low side line to the process tube of the com-
pressor.
3. Connect the high side line to the process tube of liquid line
strainer.
NOTE: If either process tube is not long enough to receive the
compression or flare fitting and still leave room for a pinch-off,
swag the tube and braze in an extra length of tubing.
4. Start the vacuum pump and open shut off valve to the high
vacuum gauge manifold only. After the compound gauge
(low side) has dropped to approximately 29 inches of
vacuum open the valve to the vacuum thermocouple gauge.
See that the vacuum pump will bank-off to a minimum of
50 microns. A high vacuum pump can only produce a
good vacuum if its oil is not contaminated.
5. If the vacuum pump is working properly, close the valve to
the vacuum thermocouple gauge and open the high and
low side valves or the high vacuum manifold set. With the
valve on the charging cylinder closed, open the manifold
valve to the cylinder.
6. Evacuate the system to at least 29 inches gauge before
opening valve to thermocouple vacuum gauge.
7. Continue to evacuate to a minimum of 250 microns. Close
valve pump and watch rate of rise. If vacuum does not rise
above 1500 microns in three minutes, system can be con-
sidered properly evacuated.
8. If thermocouple vacuum gauge continues to rise and levels
off at about 5000 microns, moisture and non-condensables
are still present. If gauge continues to rise a leak is present.
Repair and re-evacuate.
9. Close valve to thermocouple vacuum gauge and vacuum
pump. Shut off pump and prepare to charge.
Charging
Charge the system with the exact amount of refrigerant.
Refer to the unit nameplate 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. After the system will take all it will take, close the valve on
the high side of the manifold.
3. Start the system and charge the balance of the refrigerant
though the low side. Do not charge in a liquid form.
4. Close the low side valve on the manifold and pinch-off both
process tubes. Remove the manifold set, crimp shut the
open ends of the process tubes and braze.
5. Recheck for refrigerant leaks.
NOTE: Do not use a refrigerant other than that shown on the
serial number identification plate.
All precautionary measures recommended by the refrigerant
manufacturers and suppliers should be observed.
Line Piercing Valves
Line piercing valves may be used for diagnosis but are not
suitable for evacuating or charging due to the minute holes
pierced in the tubing.
Line piercing valves must not be left on the refrigerant system.
The connection between the valve and the refrigerant tubing is
not hermetically sealed and will eventually leak.
Open Lines
During any processing of the refrigeration system the lines
should never be left open to atmosphere since water vapor will
enter and add to the problem of proper evacuation.
Operating Test
The final step in a successful repair is an accurate operating
test. Follow the Cooling and Heating Performance tests pro-
vided to make sure the product is again performing to design
standards.
SERVICING