Servicing should only be performed by a Qualified Service Agent
37
OPERATION & SERVICE
Contactor Coil Voltage Test - At Contactor
This test procedure will measure contactor coil voltage at the contactor.
1
Ensure tank temperature is less than 100°F/38°C - dump water to lower tank temperature if necessary.
2
Adjust the temperature settings to ensure a call for heat is active for all heating elements. Raise the
Operating Set Point to 140°F or higher. Set all Differentials at 2°F - see pages 61 and 62.
3
Using an AC volt meter; set the volt meter to an AC voltage range just above 120 VAC.
4
Touch the two volt meter probes to the contactor coil wiring terminals on the contactor. Repeat this
procedure at each contactor being tested. There should be approximately 120 volts present between the
two terminals.
Service Warning:
Be extremely careful when performing this test procedure; volt meter probes are routed
between wires in tight proximity - there will be high voltage present at all terminals and wiring to the
contactors.
If there is no voltage present proceed to the Contactor Coil Voltage - At CCB test on page 38.
If the measured voltage is considerably less than 120 volts and/or the contactors chatter (open and close
rapidly) ensure the Control Circuit Transformer is wired correctly - see pages 39 & 40.
If the measured voltage is approximately 120 volts the contactor should close it’s switch contacts. If the
contacts are closed the contactor coil is operating properly.
If the measured voltage is approximately 120 volts and the contactor’s switch contacts do not close - the
contactor is defective and must be replaced. When replacing a contactor that has failed in this way check
all wiring between the contactor coil and the J4 or J17 wiring terminals on the CCB (see pages 50 - 52) for
pinched or shorted wires - repair or replace damaged wiring as necessary.
Service Note:
A continuity test can also be performed on contactor coils to determine if the failure is due to
an open coil winding. Secure power to the water heater at the main breaker or disconnect switch,
disconnect both wires to the contactor coil and check for continuity between the two terminals using an
ohm meter. If a contactor has an open coil the contactor must be replaced. Check all wiring between the
contactor coil and the J4 or J17 wiring terminals on the CCB (see pages 50 - 52) for pinched or shorted
wires - repair or replace damaged wiring as necessary.
3 Pole Contactor Side View
Electromagnetic
Contactor Coil Wiring
Terminals 120 VAC
4 Pole Contactor Side View
