7B – 14 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
MAINTAINING CHEMICAL STABILITY
IN THE REFRIGERATION SYSTEM
The efficient operation and life of the air conditioning
system is dependent upon the chemical stability of the
refrigeration system. When foreign materials, such as
dirt, air, or moisture, contaminate the refrigeration sys-
tem, they will change the stability of the refrigerant and
the PAG compressor oil. They will also affect the pres-
sure-temperature relationship, reduce efficient opera-
tion, and can possibly cause interior corrosion and
abnormal wear of moving parts.
Observe the following practices to ensure chemical sta-
bility in the system:
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Wipe away dirt or oil at and near any connection be-
fore opening that connection. This will reduce the
chance of dirt entering the system.
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Cap, plug, or tape both sides of a connection as soon
as possible after opening the connection. This will
prevent the entry of dirt, foreign material, and mois-
ture.
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Keep all tools clean and dry, including the manifold
gauge set and all replacement parts.
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Use a clean and dry transfer device and container to
add PAG refrigerant oil. This will ensure that the oil
remains as moisture-free as possible. Refer to “Dis-
charging, Adding Oil, Evacuating and Charging Pro-
cedures for A/C System” in this section.
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Have everything you need ready to allow you to per-
form all operations quickly when opening an A/C sys-
tem. Do not leave the A/C system open any longer
than necessary.
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Evacuate and recharge any A/C system that has
been opened. Refer to “Discharging, Adding Oil, Eva-
cuating and Charging Procedures for A/C System” in
this section for the instructions to perform this proce-
dure properly.
All service parts are dehydrated and sealed before ship-
ping. They should remain sealed until just before making
connections. All the parts should be at room tempera-
ture before uncapping. This prevents condensation of
moisture from the air from entering the system. Reseal
all parts as soon as possible if the caps have been re-
moved but the connections cannot be made promptly.
DISCHARGING, ADDING OIL,
EVACUATING, AND CHARGING
PROCEDURES FOR A/C SYSTEMS
Caution: Use only refillable refrigerant tanks that
are authorized for the charging station being used.
The use of other tanks may cause personal injury or
void the warranty. Refer to the manufacturer’s in-
structions for the charging station.
Caution: To avoid personal injury, always wear
goggles and gloves when performing work that in-
volves opening the refrigeration system.
A charging station discharges, evacuates, and re-
charges an air conditioning system with one hook-up.
Filtering during the recovery cycle together with filtering
during the evacuation cycle ensures a supply of clean,
dry refrigerant for A/C system charging.
Notice:
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Never use the R-134a charging station on a system
charged with R-12. The refrigerants and the oils are
not compatible and must never be mixed in even the
smallest amount. Mixing refrigerant residue will dam-
age the equipment.
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Never use adapters which convert from one size fit-
ting to another. This will allow contamination which
may cause system failure.
Charging Station Setup and Maintenance
Refer to the manufacturer’s instructions for all initial set-
up procedures and all maintenance procedures. There
are many charging stations available. All perform the
various tasks required to discharge the system and re-
cover refrigerant, evacuate the system, add a measured
amount of oil, and recharge an air conditioning system
with a measured amount of refrigerant.
Control Panel Functions
A charging station will have controls and indicators to al-
low the operator to control and monitor the operation in
progress. Refer to the manufacturer’s instructions for
details. These can be expected to include:
1. Main Power Switch: The main power switch supplies
electrical power to the control panel.
2. Display: The display shows the time programmed for
vacuum and the weight of the refrigerant pro-
grammed for recharging. Refer to the manufacturer’s
instructions for detailed programming information.
3. Low Side Manifold Gauge: This gauge shows the
system’s low side pressure.
4. High Side Manifold Gauge: This gauge shows the
system’s high side pressure.
5. Controls: This will contain the controls that control
various operating functions.
6. Low Side Valve: This valve connects the low side of
the A/C system to the unit.
7. Moisture Indicator: This indicator shows if the refrig-
erant is wet or dry.
8. High Side Valve: This valve connects the high side of
the A/C system to the unit.