FB, FE, FF1E, FFM, FG, FH, FJ, FMA, FT, FV, FX, FY, FZ, F54, PF: Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
3
the relay to close its normally-open contacts, turning on fan.
When thermostat no longer calls for the fan, the signal sent to
relay is turned off and relay opens causing fan to turn off after a
90-second fan-off delay.
b. Sequencer/Electric Heat Relay Interlock
The fan will also operate whenever there is a call for electric
heat, even if fan relay is not energized. This happens because fan
is interlocked with first stage of electric heat through the
normally-closed contact of fan relay.
NOTE: The fan interlock is only connected to first stage electric heat
(W2). W3 and E do not contain an interlock with fan. See outdoor
thermostat installation instructions when electric heat staging is desired.
Electric Heat
When thermostat calls for electric heat, a 24VAC signal is sent to
sequencer/heat relay through W2, causing first stage to turn on. W3 and
E also receive signal if wired in with W2. If W3 and E are not wired to
W2, the sequencers/heat relays can be controlled individually to stage
additional electric heat. The sequence control is described in the
following section:
1. W2
When thermostat sends a signal to W2, a 24VAC signal is applied
across sequencer/relay No. 1, causing it to close. When
sequencer/relay No. 1 closes, first stage of electric heat is
energized. In straight electric heat, fan is also energized through the
normally closed contacts of fan relay. In cooling, heat pump, or
manual fan mode, fan will already be running since fan relay would
have been energized. When thermostat stops calling for electric
heat, the 24VAC signal to sequencer/relay No. 1 turns off and
sequencer opens after a delay of 60 to 90 seconds. Heaters equipped
with relays will be de-energized immediately. When
sequencer/relay opens, first stage of heat turns off along with fan,
providing thermostat is not calling for the fan.
2. W3
When a signal is sent to W3, a 24VAC signal to sequencer/relay No.
2 causes it to close, with second stage of electric heat turning on.
The 24VAC signal applied to sequencer/relay No. 1 causes fan to
operate. Timing is such that sequencer/relay No. 1 will turn on
before sequencer/relay No. 2. When signal to W3 is turned off,
sequencer/relay No. 2 opens. If W2 is also satisfied, first stage of
electric heat and fan will also turn off, providing thermostat is not
calling for the fan.
3. E
When thermostat sends a signal to E, a 24VAC signal is sent to
sequencer/relay No. 3. The 24VAC signal applied to
sequencer/relay No. 3 turns on third stage of electric heat. The
24VAC signal applied to sequencer/relay No. 1 turns on first stage
of electric heat and fan. When thermostat stops calling for electric
heat, the signal to sequencers/relays 1, 2, and 3 are turned off, and
sequencers/relays open. This causes electric heat to turn off with
fan, providing thermostat is not calling for the fan.
NOTE: Electric heaters are factory wired with all stages tied together. If
independent staging is desired, consult outdoor thermostat installation
instructions, or corporate thermostat instructions.
Troubleshooting the Printed Circuit Board
(CES013000-00, 01 / HK61EA002 / HK61EA006)
Use wiring schematics shown in Fig. 1 and Fig. 2 as a guide in
troubleshooting PCB unless otherwise noted.
If Fan Will Not Turn On from Thermostat:
• IF THERE IS NO HIGH VOLTAGE TO TRANSFORMER:
(1.) Check plug/receptacle connection. This supplies power
from heaters to PCB Fan Relay. Be sure plug is connected
properly.
(2.) Check sequencer/relay No. 1 and plug wiring. Yellow wire
should be connected to Pin No. 9 of plug and to limit switch.
Black wire should be connected to Pin No. 7 of plug and to
sequencer/relay No. 1.
(3.) Check field power leads L1 and L2. If these are not
receiving power, system cannot function.
• IF TRANSFORMER HAS HIGH VOLTAGE APPLIED TO IT:
(1.) Check low-voltage transformer leads R (red) and C
(brown). Be sure they are wired to correct locations.
(2.) Check output voltage of transformer secondary side R (red)
and C (brown). Be sure transformer output is between
18VAC and 30VAC. If transformer output is incorrect and
transformer is receiving correct input voltage (208V or
230V), then transformer needs to be replaced with
recommended transformer. If no problem exists with
transformer secondary, proceed to items 3 and 4.
(3.) Check low-voltage fuse shown in Fig. 1 or Fig. 2. If fuse is
blown, replace it with an identical 5A fuse. The transformer
cannot supply power to board with fuse blown or loose. If
fuse blows when unit has power applied to it, the system
most likely has one of the following problems:
• Check all 24V wiring for an electrical short.
• The maximum load on transformer is 40VA. If load on
transformer is excessive, the low-voltage 5A fuse will
blow to protect transformer. If load exceeds VA rating of
transformer, a larger VA rated transformer needs to be
installed. Check sequencers/relays for excessive current
draw.
• Check wiring of heaters. If a heater is miswired, fuse may
blow. If a heater is miswired, correct miswiring by
comparing it to heater wiring label.
(4.) Check connections on primary side of transformer. If they
are not connected properly, the transformer secondary
cannot supply the 24V signal to energize fan relay. If
transformer is receiving correct primary voltage but is not
putting out correct secondary voltage, transformer needs to
be replaced.
If Electric Heat Stages Will Not Turn On But Fan Will Turn On:
• IF THERE IS NO HIGH VOLTAGE TO TRANSFORMER:
(1.) Check plug connection between heaters and board. This
supplies power to transformer and fan. Be sure plug is
connected properly.
(1.) Check sequencer/relay No. 1 and plug wiring. Yellow wire
should be connected to Pin No. 9 of plug and to limit switch.
Black wire should be connected to Pin No. 7 of plug and to
sequencer/relay No. 1.
(1.) Check incoming high-voltage power leads. If these are not
receiving power, system cannot function.
• IF TRANSFORMER HAS VOLTAGE APPLIED TO IT:
(1.) Check low-voltage transformer leads R (red) and C
(brown). Make sure they are wired to correct location. The
unit will not function without proper connections.
(1.) Check output voltage of transformer secondary side R (red)
and C (brown). If transformer output is low (less than
18VAC), refer to items 3 and 4 of previous “IF
TRANSFORMER HAS HIGH VOLTAGE APPLIED TO
IT” section.
• IF TRACES ARE OVERHEATED ON BACK OF PCB:
Usually whenever a trace is blown on PCB, it means either there
has been a high-voltage short or high voltage has been applied to
low-voltage circuit. This can be prevented by making sure PCB is
wired correctly before PCB has power applied to it.
• If Transformer Fuse Keeps Blowing:
When low-voltage fuse blows, it means transformer would have
blown if fuse had not been in circuit to protect it. The fuse usually
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