Test 2: Polarity Check - A.O. Smith SERIES 120 Service Handbook

TEST 2: POLARITY CHECK

Conditions:
• No hot water
• Green "Power" LED is on.
• Tank is more than 5° F below temperature dial setting.
• Red ignition control board diagnostic LED is flashing 6 times between pauses.
• Red, diagnostic "Call for Heat" LED-OFF.
TEST 2
IF.........
115-125 VAC is not present
Voltage is present white (right terminal) to ground
but not black (center terminal) to ground
Servicing should only be performed by a Qualifi ed Service Agent
TROUBLESHOOTING
BL
BR
R
1a 1 1b
BK
R
W
IGNITOR/FLAME
SENSOR
R
R
120 VAC CIRCUIT
FACTORY INSTALLED
BY INSTALLER
W
Polarity Check
Check from on/off switch center and white wire terminals to ground
then............
see Test 1.
reverse supply wire connections. Polarity is reversed.
Figure 20
120 V.
TO EARTH
GROUND
HOT 120 VAC
NEUTRAL
EARTH GROUND
Figure 21
28
Ground