ASPT Service Manual

Table Of Contents
SERVICING
92
Brazing Materials










to protect heat sensitive components such as service
valves and TXV valves.
Copper to Copper Joints - Sil-Fos used without ux
(alloy of 15% silver, 80% copper, and 5% phosphorous).
Recommended heat 1400°F.
Copper to Steel Joints - Silver Solder used without
a ux (alloy of 30% silver, 38% copper, 32% zinc).
Recommended heat - 1200°F.

WARNING



WARNING





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. After repair, repeat
the pressure test. If no leaks exist, proceed to system
evacuation.
Evacuation
WARNING



WARNING




compressors, do not allow suction pressure at service

system down for repair. Outdoor section, depending on
line set length and amount of charge in system, may

This is the most important part of the entire service
procedure. The life and e󰀩ciency 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 250 microns
or less and a vacuum gauge to give a true reading of the
vacuum in the system.

pump or run when under a high vacuum. Motor
damage could occur.
Condensing unit liquid and suction valves are closed to
contain the charge within the unit. The unit is shipped with
the valve stems closed and caps installed. Do not open
valves until the 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 suction
and liquid service valves. Using both valves is necessary
as some compressors create a mechanical seal separating
the sides of the system.
3. Close pump valve and hold vacuum for 10 minutes.
Typically pressure will rise during this period.