Step 4: Test For 24Vac Between Black And Yellow On Damper Pc Board; Step 5: Wire Harness Test - A.O. Smith BTR 120-400 Service Handbook

STEP 4: TEST FOR 24VAC BETWEEN BLACK AND YELLOW ON DAMPER PC
BOARD
IF
24VAC is present
24VAC is not present.

STEP 5: WIRE HARNESS TEST

CONDITION:
• Damper Open, no 24VAC to module "24VAC" terminal.
Test for 24 VAC between terminal 24V on the IID module, and 24V GND.
IF
24VAC is present
24VAC is not present.
Note: This test may be easier to conduct by removing the red wire from the IID terminal. Test for 24 VAC
between the red wire and ground. Reconnect the red wire to the 24V terminal after the test.
Servicing should only be performed by a Qualified Service Technician
THEN
• This is correct - Continue to Step 5.
• Check Service Switch position.
• Check the harness plug connections.
• Check that cam on shaft rotates with shaft.
• Replace the damper assembly.
THEN
• This is correct - Continue to Step 5.
• Check Service Switch position.
• Check the harness plug connections.
• Check that cam on shaft rotates with shaft.
• Replace the damper assembly.
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