- 22 -
STEP
ACTION
YES
NO
GO TO
26.
Do the main burners stay on longer than a few seconds?
36
40
27.
Turn off the power and disconnect the jumpers across the R, W/W1, and W2 thermostat
terminals.
28
28.
Connect a DC microampmeter in series with the flame sensor wire.
29
29.
Turn power on and jumper R, W/W1, and W2 thermostat terminals.
30
30.
Is the DC current below .5 microamps?
32
31
31.
Check connections and retry. If current is near typical value (4.0 to 6.0 microamps) and main
burners will not stay on longer than a few seconds, check the following:
- Flue gas leak into vestibule.
- Inadequate flame carryover on rough ignition.
- Low inlet gas pressure.
- Low manifold pressure. Reference installation instructions for proper manifold pressure.
- Slow opening gas valve. Gas should flow at full pressure within 4 seconds after the gas
valve is energized.
If the above items are OK replace the modulating furnace control.
15
32.
Clean flame sensor with fine steel wool and make sure it is properly positioned then recheck
current. Current is typically 4.0 to 6.0 microamps.
33
33.
Is current near typical value?
35
34
34.
Replace electrode.
8
35.
Will main burners ignite and stay on?
8
13
36.
Do you have burner pulsation’s?
37
49
37.
Check the following:
- Ensure there are no flue gas leaks in the vestibule.
- Ensure vent and combustion-air pipes are not reversed.
- Burner orifice size and alignment.
- Inadequate flame carryover.
- Add restriction to combustion-air pipe or lengthen a few feet if possible.
15
38.
While the unit is operating in minimum heat jumper R and W2.
39
39.
Do you have burner pulsation’s in maximum heat?
37
8
40.
Turn off the power and disconnect the jumper across the R and W/W1 thermostat terminals.
41
41.
Turn power on and jumper R, W/W1, and W2 thermostat terminals.
42
42.
Do the main burners ignite?
43
25
43.
Do the main burners stay on longer than a few seconds?
44
27
44.
Do you have burner pulsation’s?
37
45
45.
Disconnect jumper from R and W2.
46
46.
Do the main burners remain ON?
47
48
47.
Furnace will operate at minimum or intermediate heat but will not ignite on intermediate
heat. Check the following:
- Inadequate flame carryover.
- Low manifold pressure. Reference installation instructions for proper manifold pressure
settings.
- Slow opening gas valve. Gas should flow at full pressure within 4 seconds after the gas
valve is energized.
- Flame sensor location.
- Hot surface igniter location.
15
48.
Furnace will not operate at minimum or intermediate heat and will not ignite on intermediate
heat. Check the following:
- Flame sensor location.
- Very low manifold pressure.
Reference installation instructions for proper manifold pressure settings. Turn rotary
adjustment switch 1 step. Repeat until furnace will operate in intermediate heat. Then set
maximum and minimum heat to the proper manifold pressure. Re-orifice if necessary.
15
49.
Do the main burners remain lit after switching to minimum-heat?
50
51
50.
Do you have burner pulsation’s in minimum heat?
37
38
51.
Furnace will not operate at minimum heat but will ignite and operate at intermediate heat.
Check the following:
- Flame sensor location.
- Minimum heat manifold pressure.
Reference installation instructions for proper manifold pressure settings. First set the
maximum heat manifold pressure then adjust the intermediate heat manifold pressure instead
of the minimum heat manifold pressure. Re-orifice if necessary.
15
440 08 4001 00
Содержание 9MAC/E series
Страница 39: ...39 Fig 2 Wiring Schematic 440 08 4001 00...
Страница 41: ...41 Figure 3 ECM Blower Motor 440 08 4001 00...
Страница 48: ...48 Replaces New Form ICP Eng 3 12 440 08 4001 00...
