189 Rev. 3
SERVICING
3. Using an ohmmeter, test the element for continuity - no
reading indicates the element is open. Replace as nec-
essary.
S-53 OUTDOOR TEMPERATURE CONTROL
(OPTIONAL ITEM)
Outdoor temperature controls (ODT or ATK) are not required
to control the electric heat in BBA/BBC blower cabinets. Elec-
tric heater operation is controlled by the thermistor located in
discharge airstream of the blower cabinet. See the "System
Operation" section for additional information.
S-100 REFRIGERATION REPAIR PRACTICE
DANGER
ALWAYS REMOVE THE REFRIGERANT CHARGE IN A
PROPER MANNER BEFORE APPLYING HEAT TO THE
SYSTEM.
When repairing the refrigeration system:
WARNING
Disconnect Electrical Power Supply:
1. Never open a system that is under vacuum. Air and mois-
ture will be drawn in.
2. Plug or cap all openings.
3. Remove all burrs and clean the brazing surfaces of the
tubing with sand cloth or paper. Brazing materials do not
flow well on oxidized or oily surfaces.
4. Clean the inside of all new tubing to remove oils and pipe
chips.
5. When brazing, sweep the tubing with dry nitrogen to pre-
vent the formation of oxides on the inside surfaces.
6. Complete any repair by replacing the liquid line drier in
the system, evacuate and charge.
BRAZING MATERIALS
Copper to Copper Joints - Sil-Fos used without flux (alloy
of 15% silver, 80% copper, and 5% phosphorous). Recom-
mended heat 1400°F.
Copper to Steel Joints - Silver Solder used without a flux
(alloy of 30% silver, 38% copper, 32% zinc). Recommended
heat - 1200°F.
S-101 LEAK TESTING
Refrigerant leaks are best detected with a halide or elec-
tronic leak detector.
However, on outdoor installed systems, provisions must be
made to shield the copper element of an halide torch from
the sun and wind conditions in order to be able to see the
element properly.
NOTE: The flame of the halide detector will glow green in the
presence of R-22 refrigerant.
For a system that contains a refrigerant charge and is sus-
pected of having a leak, stop the operation and hold the ex-
ploring tube of the detector as close to the tube as possible,
check all piping and fittings. If a leak is detected, do not
attempt to apply more brazing to the joint. Remove and cap-
ture the charge, unbraze the joint, clean and rebraze.
For a system that has been newly repaired and does not
contain a charge, connect a cylinder of refrigerant through a
gauge manifold to the liquid and suction line dill valves and/or
liquid line dill valve and compressor process tube.
NOTE: Refrigerant hoses must be equipped with dill valve
depressors or special adaptors must be used. Open the
valve on the cylinder and manifold and allow the pressure to
build up within the system. Check for and handle leaks, as
described above. After the test has been completed, remove
and capture the leak test refrigerant.
S-102 EVACUATION
This is the most important part of the entire service proce-
dure. The life and efficiency 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 per-
formance.
Moisture chemically reacts with the refrigerant and oil to form
corrosive hydrofluoric and hydrochloric acids. These 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 equiva-
lent to 25 microns absolute and a thermocouple vacuum gauge
to give a true reading of the vacuum in the system
NOTE: Never use the system compressor as a vacuum pump
or run when under a high vacuum. Motor damage could oc-
cur.
WARNING
SCROLL COMPRESSORS. DO NOT FRONT SEAT THE
SERVICE VALVE(S) WITH THE COMPRESSOR OPERAT-
ING IN AN ATTEMPT TO SAVE REFRIGERANT. WITH
THE SUCTION LINE OF THE COMPRESSOR CLOSED OR
SEVERELY RESTRICTED, THE SCROLL COMPRESSOR
CAN AND WILL DRAW A DEEP VACUUM VERY QUICKLY.
THIS VACUUM CAN CAUSE INTERNAL ARCING OF THE
FUSITE RESULTING IN A DAMAGED OR FAILED COM-
PRESSOR.
1. Connect the vacuum pump, vacuum tight manifold set
with high vacuum hoses, thermocouple vacuum gauge
and charging cylinder as shown.
