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Table 12. Separated combustion tubular blower troubleshooting guide (continued)
SYMPTOMS
K. Blower will not run.
L. Blower motor turns on and off while burner is
operating.
M. Blower motor will not stop.
N. Not enough heat.
O. Too much heat.
P. Noisy blower/motor.
Q. Cold air is delivered during heater operation. 1. Incorrect manifold pressure or input.
GKNE-SVX001B-EN
POSSIBLE CAUSE(S)
1. Loose electrical connections.
2. Defective motor or overload.
3. Defective control board.
4. Contactor or starter overload tripped.
5. Broken belt.
1. Motor overload protection is tripping.
2. Loose wiring or connection.
3. Control board is defective.
1. Control board is in flame failure mode.
2. Improperly wired blower circuit.
3. Control board is defective.
1. Incorrect gas input.
2. Heater undersized.
3. Thermostat malfunction.
4. Heater cycling on limit.
5. Incorrect orifice sizes.
1. Unit is over fired.
2. Thermostat malfunction.
3. Heater runs continuously.
4. Defective gas valve.
5. Excessive gas supply pressure.
6. Excessive static pressure.
1. Blower wheel loose.
2. Blower wheel is dirty.
3. Blower wheel is rubbing on housing.
4. Bearings are dry.
5. Pulley is loose.
2. Air throughput too high.
Gas Input Rate
CORRECTIVE ACTION
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.
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.
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
flash code mode, replace board.
1. Refer to "Gas Input Rate"
2. Is the heater output sized correctly for the heat
loss of the space? Has the space been enlarged?
Is the heater located in the space properly (see
"Installation")?
3. Check thermostat circuit; 24V on terminals "R"
and "W" on terminal strip.
4. Check air movement across heat exchanger.
Check voltage and amps at the blower motor.
Check gas input to ensure unit is not over fired.
Check heat exchanger to ensure unit is not
dirty.
5. Check orifice size (Refer to "Gas Input Rate"),
replace if necessary.
1. Refer to "Gas Input Rate." Check orifice size.
Replace if too large.
2. Check thermostat for operation, to ensure
circuit open and closes.
3. Check wiring per diagram. Check operation at
the gas valve. Look for a short in thermostat
circuit.
4. Replace valve and check pressure setting (See
Table 4 "Gas Piping Requirements").
5. Refer to "Pipe Installation" and Table 4 - "Gas
Piping Requirements."
6. Adjust blower sheave to correct RPM - See
"Blower Set Up and Adjustment."
1. Replace or tighten.
2. Clean blower wheel.
3. Realign blower wheel.
4. Oil bearings on blower motor. (Refer to label on
motor.)
5. Check Blower and Motor pulleys. Replace or
tighten as necessary.
1. Test and reset manifold pressure (see Table 4 -
"Gas Piping Requirements").
2. Check Blower and Motor pulleys. Replace or
tighten as necessary.
33
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