Daikin DBG Series, Service Instructions Manual

Page: 27 / 108

SERVICING
27
S-4 CHECKING TRANSFORMER
AND CONTROL CIRCUIT
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.
A step-down transformer (either 208-240, 460 or 575 volt
primary to 24 volt secondary) is provided with each unit.
This allows ample capacity for use with resistance heaters.
WARNING
Disconnect ALL power before servicing.
1. Remove control panel cover to gain access to transformer.
With power ON:
WARNING
Line Voltage now present.
2. Using a voltmeter, check voltage across secondary voltage
side of transformer (R to C).
3. No voltage indicates faulty transformer, bad wiring, or bad
splices.
4. Check transformer primary voltage at incoming line voltage
connections and/or splices.
5 If line voltage available at primary voltage side of transform-
er and wiring and splices good, transformer is inoperative.
Replace.
S-7 CHECKING CONTACTOR AND/OR RELAYS
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.
The compressor contactor and other relay holding coils are
wired into the low or line voltage circuits. When the control
circuit is energized, the coil pulls in the normally open con-
tacts or opens the normally closed contacts. When the coil
is de-energized, springs return the contacts to their normal
position.
NOTE
: Most single phase contactors break only one side
of the line (L1), leaving 115 volts to ground present at most
internal components.
1. Remove the leads from the holding coil.
2. Using an ohmmeter, test across the coil terminals.
If the coil does not test continuous, replace the relay or
contactor.
S-8 CHECKING CONTACTOR CONTACTS
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. Disconnect the wire leads from the terminal (T) side of
the contactor.
2. With power ON, energize the contactor.
3. Using a voltmeter, test across terminals.
A. L1-L2, L1-L3, and L2-L3 - If voltage is present, pro-
ceed to B. If voltage is not present, check breaker or
fuses on main power supply..
B. T1-T2, T1-T3, and T2-T3 - If voltage readings are not
the same as in "A", replace contactor.
VOLT/OHM
METER
CC
Ohmmeter for testing holding coil
Voltmeter for testing contacts
T1
L1
T3
L3
T2
L2
TESTING COMPRESSOR CONTACTOR
(ThreePhase)
S-9 CHECKING FAN RELAY CONTACTS
DCG:
The fan relays are incorporated into the control board. See
section S-313 for checking control board for single phase
gas models.
For 3 phase and belt drive models, the procedure for testing
the fan relay contacts will be the same as checking the
compressor contactor contacts (See section S-8).