HKP Service Manual

SERVICING
33
WARNING
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:
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.
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
(NITROGEN OR NITROGEN-TRACED)
WARNING
WARNING
Pressure test the system using dry nitrogen and soapy water
to locate leaks. If you wish to use a leak detector, charge the
system to 10 psi using the appropriate refrigerant then use
nitrogen to finish charging the system to working pressure,
then apply the detector to suspect areas. If leaks are found,
repair them. After repair, repeat the pressure test. If no leaks
exist, proceed to system evacuation.
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.