Nordyne E2EB 010H, Service Manual

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6 E2 Service Manual
Sequencer (Figure 2)
In general all sequencers operate the same way. In
some applications one sequencer may be sufficient
(10 and 12 kw models) in other applications. One two
or more sequencers may be required.
Important: Sequencers should never be mixed. If
different brands of sequencer are used and their timing
may be different.
Testing Sequencer
1. Shut off the power supply to the furnace, there
could be two circuits. Be sure both "A" and "B"
circuits are de-energized.
a. Remove all wires from the sequencer (making
note of wire color and terminal location). The
bi-metal heater portion of the sequencer will be
unmarked and at the bottom, closest to the
mounting plate. The switching portion will be
marked M1 through M8 depending on the
number of switches. Refer to unit wiring
diagram.
b. With an ohmmeter, test for continuity across
the bi-metal heater terminals. There should be
70 to 90 ohms of resistance. If the meter reads
no continuity, the bi-metal heater is open and
must be replaced. The OHMS value should be
70 to 90 across the bi-metal.
Figure 2. Sequencer
c. With an ohmeter check all switches in the
sequencer. They are labled M1-M2, M3-
M4...refer to Figure 2. All of the switches should
be open and have no continuity.
2. With all power on to furnace, and thermostat
contacts closed: using a voltmeter (set scale for
220 vac.) On contact terminals of sequencer,
check each set of terminals of sequencer, check
each set individually. If you read voltage, contacts
are open. If you do not read voltage, contacts are
closed. Allow a maximum time (110 seconds) for
heater to close contacts. If any of the contacts
remain open after three minutes the sequencer is
defective and should be replaced.
Indoor Coil
(optional)
Coil Air Filters
(used with indoor coil)
Furnace Air Filter
(NOT used with indoor coil
and coil air filters)
Data Label
Control Panel Cover
(right)
Control Panel Cover (left)
Circuit Breakers
A/C or H/P Relay Box (optional)
Blower
Blower Selector Switch
(next to blower)