SERVICING
33
S-17D OPERATION TEST
If the voltage, capacitor, overload and motor winding test fail
to show the cause for failure:
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 unit wiring from disconnect switch and wire a test
cord to the disconnect switch.
NOTE:
The wire size of the test cord must equal the line wire
size and the fuse must be of the proper size and type.
2. With the protective terminal cover in place, use the three
leads to the compressor terminals that were disconnected
at the nearest point to the compressor and connect the
common, start and run clips to the respective leads.
3. Connect good capacitors of the right MFD and voltage
rating into the circuit as shown.
4. With power ON, close the switch.
WARNING
Line Voltage now present.
A. If the compressor starts and continues to run, the cause
for failure is somewhere else in the system.
B. If the compressor fails to start - replace.
S-18 TESTING CRANKCASE HEATER (OPTION-
AL ITEM)
The crankcase heater must be energized a minimum of four
(4) hours before the condensing unit is operated.
Crankcase heaters are used to prevent migration or accumu-
lation of refrigerant in the compressor crankcase during the off
cycles and prevents liquid slugging or oil pumping on start up.
A crankcase heater will not prevent compressor damage due
to a floodback or over charge condition.
WARNING
Disconnect ALL power before servicing.
1. Disconnect the heater lead in wires.
2. Using an ohmmeter, check heater continuity - should test
continuous. If not, replace.
The condition of the scroll flanks is checked in the following
manner.
1. Attach gauges to the high and low side of the system.
2. Start the system and run a “Cooling Performance Test.
If the test shows:
a.
Below normal high side pressure.
b.
Above normal low side pressure.
c.
Low
temperature difference across coil.
d.
Low amp draw at compressor.
And the charge is correct. The compressor is faulty - replace
the compressor.
S-50 CHECKING HEATER LIMIT CONTROL(S)
(OPTIONAL ELECTRIC HEATERS)
Each individual heater element is protected with an automatic
rest limit control 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.
to 160°F and close at approximately 110°F.
WARNING
Disconnect ALL power before servicing.
1. Remove the wiring from the control terminals.
2. Using an ohmmeter test for continuity across the nor-
mally closed contacts. No reading indicates the control
is open - replace if necessary. Make sure the limits are
cool before testing.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND
.
S-52 CHECKING HEATER ELEMENTS
Optional electric heaters may be added, in the quantities
shown in the spec sheet for each model unit, to provide
electric resistance heating. Under no condition shall more
heaters than the quantity shown be installed.
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. 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 nec-
essary.
Summary of Contents for DBC Series
Page 51: ...51 ACCESSORIES GAS ELECTRIC ...
Page 52: ...ACCESSORIES 52 GAS ELECTRIC ...
Page 53: ...53 ACCESSORIES ...
Page 54: ...ACCESSORIES 54 ...
Page 95: ...95 DBC COMMERCIAL 15 25 Ton Packaged Air Conditioner Unit WIRING DIAGRAMS ...
Page 100: ...100 DBG COMMERCIAL 15 25 Ton Packaged Gas Electric Unit WIRING DIAGRAMS ...
