P/N 240008111, Rev. G [06/18/10] 39
output of the 24v transformer (located in the
air handler) to ensure that the control voltage
is present.
EMI heat pump systems utilize a revers-
ing valve is that is energized in the cooling
mode.
The reversing-valve signal is provided •
through the orange (O) low volt wire of
the air handler or thermostat.
It should remain energized constantly •
as long as the indoor unit or thermostat
remains in cooling mode.
To check for 24v reversing valve voltage, •
at the outdoor unit, place a voltmeter
across the brown (C) and orange (O)
wires while in the cooling mode.
Heating
Heat pump units can accommodate two-stage
heating when an optional electric strip heater
is present along with a heat pump condenser.
e rst stage is the compressor and the sec-
ond is electric heat.
e air handler or wall thermostat will cycle
the condenser through the yellow (Y) wire as
it does in cooling, however the reversing valve
will not be energized.
To check for a condenser signal, place the
indoor unit or wall thermostat in heating.
Next place the set-point temperature one •
degree above room temperature to call the
rst stage of heating.
en, with a voltmeter, check for 24 volts •
across the yellow (Y) and brown (C)
wires at the condenser.
The electric heat should be off at this •
point. Select a setpoint temperature that
is more than two degrees above the room
temperature to call for the second stage
of heating.
e electric heat should energize along •
with the 24v compressor signal between
Y and C.
Verify that the amp draw corresponds •
with to the electric heat rating.
e following current values apply when the
unit is connected to a 230V power supply.
ese values include indoor fan motor cur-
rent. If the supply power is dierent, this will
aect the amp draw of the heater.
5kw = 22.3 amps
3kw = 13.5 amps
Units with electric heat utilize a control relay
located on the circuit board in the control
box.
As a safety feature, an auto-reset limit switch
located on the heater assembly will interrupt
power to the heater should an over-heat con-
dition occur.
Each electric heat assembly is also equipped
with a one-time fuse link. Should electric heat
temperatures rise above the auto reseing
limit switch, a non-reseing, the one-time
fuse link will open and the heater will remain
o. To restart, a new fuse link is required.
Units with condensate pumps
EMI Air Handlers are available with an op-
tional condensate pump. Condensate pumps
are recommended when it is not possible to
gravity drain the condensate from the indoor
unit.
e maximum li for the pumps will vary.
Consult the pump instructions for the maxi-
mum li.
Condensate generated by the air handler will
collect in the pump’s reservoir.
When the water level is high enough a the •
pump motor will energize clearing the
water from the reservoir.
Should the water exceed the maximum •
preset level, a safety switch will open,
interrupting the (Y) signal to the con-
denser.
This will prevent the air handler from •
generating more condensate.
Troubleshooting (continued)
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