68-0237-2 G.H. Rev. 11-02 www.honeywell.com/yourhome
Automation and Control Solutions
Honeywell Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North 35 Dynamic Drive
Golden Valley, MN 55422 Scarborough, Ontario
M1V 4Z9
Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.
EMM-3U UNIVERSAL ELECTRONIC MINIZONE™ PANEL
Fig. 21. Thermostat is calling for heating but the Heat LED is not turning red to show a heat call.
Ye s
Ye s
Is the
thermostat calling
for heat?
Ye s
No
Make sure thermostat is
calling for heat. Raise
the setpoint and verify the
thermostat is calling for heat.
Ye s
No
Is there
24 vac at R and C on
the transformer
contacts?
Ye s
No
Check the transformer
for 24 vac.
No
The
thermal fuse has
tripped because of a high amp
draw. Remove the R wire on
the transformer contacts from the board
for 5 minutes and allow the board to reset. Take
the thermostat and damper wires off from
each zone before you re-attach the
transformer R wire. Is there
voltage at R-C on all
of the zones?
Re-attach each zone thermostat wire. Replace
each zone separately, checking after each
zone is attached if the thermal fuse
has tripped by checking voltage across R
and C on that zone. After attaching the
thermostat wires, replace each zone motor
wires, again checking the thermal fuse to
see if it trips. This step-by-step process
should help you identify what is tripping the
thermal fuse on the board.
Is there
24 vac on all the zones
at R-C?
The board may have been damaged.
Take the transformer R wire off again
for 10 minutes. After 10 minutes re-
attach that R wire and press the BOOT
button. Check voltage at R-C on all
the zones. If no voltage at R-C,
call Honeywell Zoning hotline,
800-828-8367.
Start
No
It could be a bad wire. If you have voltage
on the panel at R-W or W1* (and R-B if there is a
wire on B) but not at the thermostat, it is a bad
wire. Check for voltage at R-Y or Y1, R-G on the
thermostat. If there is voltage, it is a bad W or W1*
or (B if you are using B) wire. If there is
no voltage at R-any other terminal on the
thermostat, it is a bad R wire.
Jumper the R wire to the W or W1* (and O/B, if your thermostat uses it
for heat changover) wire on the thermostat. If the HEAT light comes
on, you have a bad thermostat. Replace thermostat. If you
jumper R-W or W1* (and O/B if you have a wire on O/B) on the thermosta
and the HEAT light does not come on, you may have a bad wire.
Try another set of wires or check continuity.
Check for
24 vac at W1-C on
the zone calling for heating.
You should have
24 vac?
No
Is
24 vac at R-W1 and
R-O/B on the
thermostat?
Ye s
Are you
using heat pump
or conventional
thermostats?
Conventional
Ye s
Do you
have the correct volt
reading at O/B-C on
the board?
Ye s
No
Check for 24 vac at W1-C on the zone that is calling for
heat. Check for 24 vac at the O/B-C on that zone.
Are you using O or B on the thermostat? If you are
using O on the thermostat, you need to place the
shunt jumper across the two pins. If you are using B,
you need to place that jumper on just one of the
pins or take it completely off. If you are using O then you
will not have 24 vac at O/B-C. If you are using B on the
thermostat, you will have 24 vac at O/B-C.
Heat pump
Is there
continuity at Rh-W1 (or Y1
for heat pump) and Rh-B on the
equipment contacts of the
EMM-3U board?
Ye s
No
Do you have
a DATS sensor hooked
to the board?
The heating equipment should be on.
Call Honeywell Zoning hotline,
800-828-8367.
*NOTE:
When using a heat pump thermostat with a single Y for first stage
heating and cooling, in the troubleshooting chart, substitute Y for W1.
Remove all wires from the board except R and C (power from the transformer).
Reboot the board. Jumper R-W or W1* (and R-O/B if you are using B from
the thermostat) on one of the zones. If the HEAT light does not come on,
call Honeywell Zoning hotline, 800-828-8367.
Remove the DATS wires from
the board. Reboot the board.
Return to "Is the thermostat
calling for HEAT" part of the
flowchart and begin
troubleshooting from that point.
No
Ye s
END
M14828A
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