A.O. Smith BTH 150 - Troubleshooting

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A. O. Smith Water Products Company Service Handbook

Irving, Texas 2000

Training Department

TROUBLESHOOTING

STEP 9 - BLOWER SPEED TEST

STEP 9. Check for 120 VAC from the back of CN 2 plug term 1 (black) to ground and from CN 2

term 2 (white) to ground.

IF… AND

terminal 1 to gnd. does not show 120 VAC

terminal 1 to gnd. does show 120 VAC

blower is running

blower is not runn

Reconnect plugs to board.

Blower operation check

• Tank must be calling for heat (minimum setting available is 80 F)

• Set multimeter to read 120 VAC

Heater models -

966 or 967

Ohms resistance

desired +/- 7.5%

BTH 120 11.5

BTH 150 AND 199 11.2

BTH 250 7.4

Note: A shorted blower motor may damage the

control board or, on BTH 250 models, the blower

speed reduction board. Conduct a continuity

check between the black and white terminals of the

C2 blower plug.

A.O. Smith BTH 150 - Troubleshooting - Continued; Blower