Condensing Unit & Heat Pump R410A Service Manual

116
SERVICING
To avoid the risk of fire or explosion, never use
oxygen, high pressure air or flammable gases for leak
testing of a refrigeration system.
WARNING
WARNING
To avoid possible explosion, the line from the
nitrogen cylinder must include a pressure regulator
and a pressure relief valve. The pressure relief valve
must be set to open at no more than 150 psig.
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 nish charging the system to working pressure, then
apply the detector to suspect areas. If leaks are found, repair
them. Aer repair, repeat the pressure test. If no leaks exist,
proceed to system evacuaon.
S-102 EVACUATION
REFRIGERANT UNDER PRESSURE!
Failure to follow proper procedures may cause
property damage, personal injury or death.
WARNING
Do not front seat the service valve(s) with the
Compressor open, with the suction line of the
comprssor closed or severely restricted.
WARNING
IMPORTANT NOTE: Because of the potenal damage to
compressors, do not allow sucon pressure at service valve to
drop below 20 PSIG when pumping unit system down for repair.
Outdoor secon, depending on line set length and amount of
charge in system, may not be able to hold the enre system
charge.
This is the most important part of the enre service procedure.
The life and eciency of the equipment is dependent upon the
thoroughness exercised by the serviceman when evacuang
air (non-condensables) and moisture from the system. Air in
a system causes high condensing temperature and pressure,
resulng in increased power input and reduced performance.
Moisture chemically reacts with the refrigerant oil to form
corrosive acids. These acids aack 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 250 microns or less and
a vacuum gauge to give a true reading of the vacuum in the
system.
NOTE: Never use the Scroll compressor as a vacuum pump or run
when under a high vacuum. Motor damage could occur.
Condensing unit liquid and sucon valves are closed to contain
the charge within the unit. The unit is shipped with the valve
stems closed and caps installed. 
system is evacuated.
1. Connect the vacuum pump with 250 micron capability to the
service valves.
2. Evacuate the system to 250 microns or less using sucon and
liquid service valves. Using both valves is necessary as some
compressors create a mechanical seal separang the sides of
the system.
3. Close pump valve and hold vacuum for 10 minutes. Typically
pressure will rise during this period.
4. If the pressure rises to 1000 microns or less and remains
steady the system is considered leak free; proceed to start-
up.
5. If pressure rises above 1000 microns but holds steady below
2000 microns, moisture and/or non-condensibles may be
present or the system may have a small leak.
6. Return to step 2: If the same result is encountered check for
leaks as previously indicated and repair as necessary then
repeat evacuaon.
7. If pressure rises above 2000 microns, a leak is present. Check
for leaks as previously indicated and repair as necessary
then repeat evacuaon.