Sterling TC - Manual (Page 26)

26
Table 9 - Tubular Blower Troubleshooting Guide (continued)
SYMPTOMS POSSIBLE CAUSE(S) CORRECTIVE ACTION
H. Condensation. 1. Improper venting.
2. Unit under fi red.
3. Building/space too cold.
1. Refer to "Installation."
2. Check gas supply pressures to unit. Refer to
"Installation."
3. Refer to "Installation."
I. Burners will not shut off. 1. Thermostat located improperly.
2. Improper thermostat wiring.
3. Shorted circuit.
4. Defective thermostat.
5. Defective/sticking gas valve.
6. Defective control board.
7. Excessive gas supply pressure.
1. Relocate thermostat away from outside wall
or drafts.
2. Check thermostat circuit for open and close
on heater terminal strip "R" and "W."
3. Check thermostat circuit for shorts or any
staples piercing wires.
4. If thermostat is calling after set point has
been satisfi ed, replace.
5. Check for 24V on gas valve terminals when
thermostat not calling. Replace if necessary.
6. Check for 24V at terminals "R" and "W." If not
present and board is not in fl ash code mode,
replace board.
7. Refer to "Pipe Installation" and Table 4 - "Gas
Piping Requirements."
J. Rapid burner cycling. 1. Loose electrical connections at thermostat or
gas valve.
2. Excessive thermostat heat anticipator setting.
3. Unit cycling on high limit.
4. Thermostat located improperly.
1. Tighten all electrical connections.
2. Adjust heat anticipator setting for longer
cycles. Refer to "Electrical Connections."
3. Check for proper air supply across heat
exchanger and proper gas supply.
4. Relocate thermostat away from outside wall
or drafts.
K. Blower will not run. 1. Loose electrical connections.
2. Defective motor or overload.
3. Defective control board.
4. Contactor or starter overload tripped.
5. Broken belt.
1. Check and tighten wires on blower circuit.
2. Test for 115V on terminal ACB Heat and "L2."
If voltage is present, replace motor.
3. Test for 115V on terminal ACB Heat and "L2."
If voltage is not present 45 seconds after trial
for ignition, replace board.
4. Test for 115V on coil of contactor. Check if
overload has tripped; reset. Check amp draw
to motor. Check incoming for power and
contactor operation.
5. Replace belt.
L. Blower motor turns on and off while
burner is operating.
1. Motor overload protection is tripping.
2. Loose wiring or connection.
3. Control board is defective.
1. Check motor amp against the motor name
plate, check voltage, replace if found
defective.
2. Check for 115V between motor leads.
3. Check terminal ACB Heat for voltage. If
voltage not constant, replace board.
M. Blower motor will not stop. 1. Control board is in fl ame failure mode.
2. Improperly wired blower circuit.
3. Control board is defective.
1. Turn 115V power off to the unit, wait 10
seconds and reapply voltage to the unit.
2. Check wiring of blower circuit to wiring
diagram.
3. If unit is not calling for heat and board is not
in fl ash code mode, replace board.