SERVICING
43
Pressure test the system using dry nitrogen and soapy
water to locate leaks. If you wish to use a leak detector,
charge the system to 10 psi using the appropriate refrigerant
then use nitrogen to finish charging the system to working
pressure, then apply the detector to suspect areas. If leaks
are found, repair them. After repair, repeat the pressure test.
If no leaks exist, proceed to system evacuation.
S-102 EVACUATION
WARNING
REFRIGERANT UNDER PRESSURE!
Failure to follow proper procedures may cause
property damage, personal injury or death.
This is the most important part of the entire service proce-
dure. 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 a system causes high condensing temperature and
pressure, resulting in increased power input and reduced
performance.
Moisture chemically reacts with the refrigerant oil to form
corrosive acids. These acids 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
equivalent to 25 microns absolute 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.
Do not front seat the service valve(s) with the
compressor open, with the suction line of the
comprssor closed or severely restricted.
WARNING
1. Connect the vacuum pump, vacuum tight manifold set
with high vacuum hoses, thermocouple vacuum gauge
and charging cylinder as shown.
2. Start the vacuum pump and open the 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 blank-off to a
maximum of 25 microns. A high vacuum pump can only
produce a good vacuum if its oil is non-contaminated.
LOW SIDE
GAUGE
AND VALVE
HIG H SIDE
GAUGE
AND VALVE
TO
UNIT SERVICE
VALVE PORTS
VACUUM PUMP
VACUUM PUMP
ADAPTER
800 PSI
RATED
HOSES
CHARG ING
CYLINDER
AND SCALE
{
R-22
MANIFOLD
EVACUATION
3. If the vacuum pump is working properly, close the valve to
the vacuum thermocouple gauge and open the high and
low side valves to the high 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 thermocouple vacuum gauge.
5. Continue to evacuate to a maximum of 250 microns.
Close valve to vacuum pump and watch rate of rise. If
vacuum does not rise above 1500 microns in three to five
minutes, system can be considered properly evacuated.
6. 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.
7. Close valve to thermocouple vacuum gauge and vacuum
pump. Shut off pump and prepare to charge.
