Instruction manual

14
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, recover
pressure and repair.
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 system.
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.
START UP AND PERFORMANCE
Even though the unit is factory charged with Refrigerant-410A, 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 instruc-
tions on the unit service panel rating plate for marking the total charge.
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.
Air conditioning systems require a specified airflow. Each ton of cooling requires
between 350 and 450 cubic feet of air per minute (CFM), or 400 CFM nominally.
Duct design and construction should be carefully done. System performance can be
lowered dramatically through bad planning or workmanship.
Air supply diffusers must be selected and located carefully. They must be sized and
positioned to deliver treated air along the perimeter of the space. If they are too
small for their intended airflow, they become noisy. If they are not located properly,
they cause drafts. Return air grilles must be properly sized to carry air back to the
blower. If they are too small, they also cause noise.
!
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.