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SERVICING
S-61A CHECKING HEATER LIMIT CONTROL(S)
Each individual heater element is protected with a limit control
device connected in series with each element to prevent
overheating of components in case of low airflow. This limit
control will open its circuit at approximately 150°F.
WARNING
HIGH VOLTAGE
Disconnect ALL power before servicing or installing
this unit. Multiple power sources may be present.
Failure to do so may cause property damage, personal
injury or death.
1. Remove the wiring from the control terminals.
2. Using an ohmmeter, test for continuity across the
normally closed contacts. No reading indicates the control
is open - replace if necessary.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND.
S-61B CHECKING HEATER FUSE LINK
(OPTIONAL ELECTRIC HEATERS)
Each individual heater element is protected with a one time fuse
link which is connected in series with the element. The fuse link
will open at approximately 333°.
WARNING
Disconnect ALL power before servicing.
1. Remove heater element assembly so as to expose fuse
link.
2. Using an ohmmeter, test across the fuse link for continuity -
no reading indicates the link is open. Replace as necessary.
NOTE:
The link is designed to open at approximately 333°F. DO
NOT WIRE AROUND - determine reason for failure.
S-62 CHECKING HEATER ELEMENTS
WARNING
Disconnect ALL power before servicing.
1. Disassemble and remove the heating element.
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
necessary.
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
HIGH VOLTAGE
Disconnect ALL power before servicing or installing
this unit. Multiple power sources may be present.
Failure to do so may cause property damage, personal
injury or death.
1. Never open a system that is under vacuum. Air and
moisture 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
prevent 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
IMPORTANT NOTE:
Torch heat required to braze tubes of various
sizes is proportional to the size of the tube. Tubes of smaller size
require less heat to bring the tube to brazing temperature before
adding brazing alloy. Applying too much heat to any tube can
melt the tube. Service personnel must use the appropriate heat
level for the size of the tube being brazed.
NOTE:
The use of a heat shield when brazing is recommended to
avoid burning the serial plate or the finish on the unit. Heat trap
or wet rags should be used to protect heat sensitive components
such as service valves and TXV valves.
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.
