SERVICING
34
1. Disassemble and remove the heating element(s).
2. Visually inspect the heater assembly for any breaks in the
wire or broken insulators.
3. Using an ohmmeter, test the element for continuity - no
reading indicates the element is open. Replace as neces-
sary.
S-100 REFRIGERATION REPAIR PRACTICE
DANGER
ALWAYS REMOVE THE REFRIGERANT CHARGE IN
A PROPER MANNER BEFORE APPLYING HEAT TO
THE SYSTEM.
These models use the FasTest Access Fitting System, with a
saddle that is either soldered to the suction and liquid lines or
is fastened with a locking nut to the access fitting box (core)
and then screwed into the saddle. Do not remove the core
from the saddle until the refrigerant charge has been
removed. Failure to do so could result in property dam-
age or personal injury.
When installing a new core or reinstalling the core after re-
moval, it is very important to note that before inserting the core
into the saddle, the core and saddle must be free of debris and
the “O” Ring must have a thin coating of refrigerant oil applied
to it. The oil is to prevent the “O” Ring from being deformed
when the core is tightened completely. The core should be
torqued to 8 ft. lb.
When repairing the refrigeration system:
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.
At any time the system has been open for repair, the factory
installed liquid line filter drier must be replaced.
BRAZING MATERIALS
Copper to Copper Joints - Sil-Fos used without flux (alloy of
15% silver, 80% copper, and 5% phosphorous). Recommended
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 electronic
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 explor-
ing 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 capture the charge,
unbraze the joint, clean and rebraze.
For a system that has been newly repaired and does not con-
tain 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 de-
pressors or special adaptor used. Open the valve on the cylin-
der 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 procedure.
The life and efficiency of the equipment is dependent upon the
thoroughness exercised by the serviceman when evacuating
air (non-condensable) and moisture from the system.
Air in a system causes high condensing temperature and pres-
sure, resulting in increased power input and reduced perfor-
mance.
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 occur.
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