Nortek Reznor UDSA-4 Manual page 37

General Troubleshooting
PROBLEM PROBABLE CAUSE
Venter motor 1. No power to unit
will not start 2. No power to venter motor
3. Integrated burner relay defective.
4. Defective venter motor.
5. Fluse blown (F3.1).
6. Fuse burner relay blown.
7. LC1 open.
8. LC3 open.
9. Unit in lock-out.
10. Room thermostat open.
Burner will 1. Main valve not operating
not light
2. Air in the gas line.
3. Gas pressure too high or too low.
4. No spark:
a) Loose wire connections.
b) Incorrect spark gap.
c) Spark cable has a short circuit to ground.
d) Spark electrode has a short circuit to ground.
e) Burner relay not grounded.
f) Unit not properly grounded.
g) Faulty burner relay.
5. Combustion airs pressure switch not closing
upon power to venter and reset lamp is burning.
Burner cycle 1. Gas pressure too high or too low.
on and off
2. Burner relay not grounded.
3. Faulty burner relay.
4. Flame sensor grounded.
5. Cracked ceramic at sensor.
6. Incorrect polarity.
Blower or 1. Motor internal thermal protection device cycling
venter motor on and off.
turns on and
off while
burner is
operating
REMEDY
1. Turn on power, check supply fuses or circuit breaker.
2. Check connections at burner relay and/or venter motor terminals.
3. Replace burner relay.
4. Replace venter motor. See Section 26.
5. Replace fuse.
6. Replace fuse.
7. a) Set heater on ventilation until LC1 closes.
b) Replace LC1.
c) Check if there is obstruction at the fan side.
8. a) Reset LC3.
b) Replace LC3.
9. Push on reset button.
10. Set thermostat above room temperature.
1. a) Check voltage on valve during ignition period.
b) Check connector on main gas valve.
c) Check connector on burner relay.
d) Replace valve.
2. Purge gas line.
3. a) Supply pressure should be 15 mbar for natural gas (UK only) or 37
mbar for propane gas (UK only).
b) Obstruction in the gas line.
c) Gas line connection diameter too small.
4. Check the following:
a) Be certain all wire connections are solid.
b) Maintain spark gap at 3 mm.
c) Replace worn or grounded spark cable.
d) Replace if ceramic spark electrode is cracked or grounded.
e) Check burner relay ground wire.
f) Make certain unit is properly fi eld grounded (earthed) and properly
phased
(L1 to hot lead, L2 to neutral).
g) If voltage is available to the burner relay and all other causes have been
eliminated, replace burner relay.
5. First check the following:
a) Make sure unit is properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
d) Replace faulty pressure switch.
1. Supply pressure should be 15 mbar for natural gas (UK only) or 37 mbar
for propane gas (UK only).
2. Check burner relay ground wire connection.
3. If (220/240) volts is available to the burner relay and all other causes have
been eliminated, replace burner relay.
4. Be certain fl ame sensor lead is not grounded or insulation or ceramic is
not cracked. Replace as required.
5. Replace sensor.
6. Check polarity switch and if necessary reverse line voltage wires to termi-
nal block connections.
1. Check motor load against motor rating plate. Replace motor if needed.
1607UDSA-4GBEN, Pag. 37/40