Installation and Maintenance Manual

Diagnostics
GTND-SVX01B-EN 47
G. Failure to ignite. 1. Gas supply is off. 1. Open all manual gas valves. Check for leaks.
2. Lack of power at unit. 2. Replace fuse or turn on power supply.
3. Thermostat not calling for heat. 3. Turn up thermostat. Check for 24 volts at terminals “R” and
“W1” on terminal strip.
4. Defective high limit. 4. Check limit switch with continuity tester. If open with no
heat present, replace limit switch.
5. Defective drafter prove switch. 5. Check switch operation to ensure switch closes after drafter
purge period. If it does not, make/check tubing
connections/blockage.
6. Improper ground. 6. Check all ground wires and connections.
7. Improper thermostat or
transformer wiring.
7. Check wiring per diagrams.
8. Ignitor defective/damaged. 8. Replace ignitor.
9. Misaligned ignitor. 9. Realign ignitor.
10. Defective gas valve. 10. Check for 24 volts at gas valve terminals during trial for
ignition period. If present with no manifold pressure,
replace gas valve.
11. Loose wiring. 11. Check and tighten all wiring connections per diagrams.
12. Blown fuse. 12. Refer to symptom Q.
H. Condensation of water vapor. 1. Improper venting. 1. Refer to “Installation: Venting,” p. 23.
2. Unit under-fired. 2. Check gas supply pressures to unit. Refer to “Installation:
Mechanical,” p. 16.
3. Building too cold. 3. Refer to “Installation: Mechanical,” p. 16.
I. Burner(s) won't turn off. 1. Poor thermostat location. 1. Relocate thermostat away from outside walls or drafts.
2. Improper thermostat wiring at gas
valve.
2. Check thermostat circuit for open and close on terminal strip
on heater “R” and “W”.
3. Short circuit. 3. Check thermostat circuit for short (such as staples piercing
thermostat wiring), and correct.
4. Defective or sticking gas valve. 4. Check for 24V at gas valve terminals when thermostat is not
calling.
5. Excessive gas supply pressure. 5. Refer to “Installation: Piping,” p. 21.
J. Rapid burner cycling. 1. Loose electrical connections at gas
valve or thermostat.
1. Tighten all electrical connections.
2. Excessive thermostat heat
anticipator setting.
2. Adjust thermostat heat anticipator for longer cycles. Refer
to “Installation: Electrical,” p. 37.
3. Unit cycling on high limit. 3. Check for proper air supply across heat exchanger and
proper gas supply.
4. Poor thermostat location. 4. Relocate thermostat.
K. Noisy power venter. 1. Power venter wheel loose. 1. Replace or tighten.
2. Power venter wheel dirty. 2. Clean power venter wheel.
3. Power venter wheel 3. Realign power venter wheel.
L. Fan will not run. 1. Loose electrical connections. 1. Check and tighten wires on fan circuit.
2. Defective motor or overload. 2. Test for 115V at terminal ACB Heat and “L2”. If voltage is
present, replace motor.
3. Defective control board. 3. Test for 115V at terminal ACB Heat and “L2” on the control
board. If voltage is not present 45 seconds after trial for
ignition, replace board.
4. Blown fuse. 4. Replace fuse.
M. Fan motor turns on and off while
burner is operating.
1. Motor overload protection is
tripping.
1. Check motor amps against motor name plate, and check
voltage. Replace if found defective.
2. Loose wiring or connection. 2. Check for 115V between motor leads.
3. Control board is defective. 3. Check terminal ACB Heat for voltage. If voltage is not
constant, replace board.
Table 11. Troubleshooting guide (continued)
Symptoms Possible Cause(s) Corrective Action