14
•
Clean the fittings before brazing.
•
Remove the cap and schrader core from service port to protect seals from heat
damage.
•
Use an appropriate heatsink material around the copper stub and the service
valves before applying heat.
•
IMPORTANT:
Do not braze any fitting with the TEV sensing bulb attached.
•
Braze the tubing between the outdoor unit and indoor coil. Flow dry nitrogen
into a service port and through the tubing while brazing.
•
After brazing – use an appropriate heatsink material to cool the joint and
remove any flux residue.
9.7 LEAK TESTING
•
Pressurize line set and coil through service fittings with dry nitrogen to 150 psig
maximum. Leak test all joints using liquid detergent. If a leak is found, repair
and repeat leak test procedures.
10.0 EVACUATION PROCEDURE
Evacuation 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 and moisture from the line set and indoor coil.
Air in the system causes high condensing temperatures and pressure, resulting in
increased power input and non-verifiable performance.
Moisture chemically reacts with the refrigerant and oil to form corrosive hydrofluoric
and hydrochloric acids. These attack motor windings and parts, causing breakdown.
After the system has been leak checked and proven sealed, connect the vacuum
pump and evacuate system to 500 microns. The vacuum pump must be connected
to both the high and low sides of the system through adequate connections. Use
the largest size connections available since restrictive service connections may lead
to false readings because of pressure drop through the fittings.
IMPORTANT:
Compressors (especially scroll type) should never be used to evacu-
ate the air conditioning system because internal electrical arcing may result in a
damaged or failed compressor.
11.0 START UP AND PERFORMANCE
Even though the unit is factory charged with R410A, the charge must be checked to
the charge table attached to the service panel and adjusted, if required. Allow a
minimum of 5 minutes running. Before analyzing charge, see the instructions on the
unit service panel rating plate for marking the total charge.
•
The service valves are not backseating valves. To open the valves, remove the
valve cap with an adjustable wrench. Insert a 3/16” or 5/16” hex wrench into the
stem. Back out counterclockwise until it stops.
•
Replace the valve cap finger tight then tighten an additional 1/8 of a turn for a
metal-to-metal seal.
12.0 CHECKING AIRFLOW
The air distribution system has the greatest effect. The duct system is totally con-
trolled by the contractor. For this reason, the contractor should use only industry-
recognized procedures.
The correct air quantity is critical to air conditioning systems. Proper operation, effi-
ciency, compressor life, and humidity control depend on the correct balance
between indoor load and outdoor unit capacity. Excessive indoor airflow increases
the possibility of high humidity problems. Low indoor airflow reduces total capacity,
and causes coil icing. Serious harm can be done to the compressor by low airflow,
such as that caused by refrigerant flooding.
!
WARNING
DO NOT USE OXYGEN TO PURGE LINES OR PRESSURIZE SYSTEM FOR
LEAK TEST. OXYGEN REACTS VIOLENTLY WITH OIL, WHICH CAN
CAUSE AN EXPLOSION RESULTING IN SEVERE PERSONAL INJURY OR
DEATH.
