SERVICING
30
1. Remove control panel cover or etc. to gain access to trans-
former.
With power ON:
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 is present at the primary voltage side of the
transformer and 24 volts is not present on the secondary
side, then the transformer is inoperative. Replace.
S-7 CHECKING CONTACTOR AND/OR RELAYS
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 contacts
or opens the normally closed contacts. When the coil is de-
energized, springs return the contacts to their normal position.
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 con-
tactor.
S-8 CHECKING CONTACTOR CONTACTS
SINGLE PHASE
1. Disconnect the wire leads from the terminal (T) side of the
contactor.
2. With power ON, energize the contactor.
Line Voltage now present.
VOLT/OHM
METER
T1
T2
L1
L2
CC
Ohmmeter for testing holding coil
Voltmeter for testing contacts
TESTING COMPRESSOR CONTACTOR
(Single Phase)
3. Using a voltmeter, test across terminals.
A.
L1 - L2 - No voltage. Check breaker or fuses on main
power supply.
B.
L2 - T1 - No voltage indicates CC1 contacts open.
If a no voltage reading is obtained - replace the contactor.
THREE PHASE
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
The fan relays are incorporated into the control board. See
section S-313 for checking control board.