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The Right Fit For Comfort
13
HEAT PUMP
(Thermostatic Drain Pan Valve)
Heat pump units are equipped with a thermostatic drain
valve that will open when outdoor temperatures fall below
50°F. This keeps the base pan free of condensate water
where it may otherwise freeze during colder outdoor tem-
peratures. As part of its normal operation, the unit will pro-
duce condensate and collect it in the base pan of the unit.
There it will be picked up by the condenser fan slinger
ring and deposited onto the condenser coil. During the
cooling season, this improves the unit’s efficiency by main-
taining adequate refrigeration system pressures.
ANTI-SHORT CYCLE TIMER
Random Start Feature (Optional)
This feature will prevent compressor short cycling and also
prevent multiple units in a single facility from simulta-
neously starting following a power outage. This delay on
break feature ensures that the compressor remains off,
between cycles, until the three-minute time delay period
has elapsed allowing system pressures to equalize be-
fore re-starting.
The random start feature, initiated after a power failure,
will add a random time delay (between 5-120 seconds) to
the three-minute anti short cycle time following a power
outage. This will stagger the starting of multiple units in a
single facility allowing a building to slowly go back on line
when power is restored.
INDOOR COIL FREEZE PROTECTION (Optional)
This feature will prevent the indoor coil from freeze up in
the cooling mode. Indoor coil freeze up can occur due to
a dirty air filter, low refrigerant charge or low room or out-
door temperatures. This in turn can cause compressor
damage. Should a freeze condition be detected, the com-
pressor and condenser fan will be switched off for a mini-
mum of three minutes and until the freeze condition is
satisfied. During this time the indoor fan will continue
to run to aid in the defrost process.
AJ4004 CONTROL BOARD (Optional)
There are two sets of jumper pins on the control board
that are factory set so there should no need to set them
later on in the field. The first is a set of three pins labeled
“HP” for selection of either a “Straight Cool” or “Heat Pump”
unit. For “Straight Cool” the center pin and outer most pin
(usually on the top) are to be jumped together. For Heat
Pump units the center pin and the pin closest to the relay
are to be jumped together.
(Figure 1)
RETROAIRE PTAC OPERATION (Continued)
The second is a set of two pins labeled “TEST”. When these
two pins are jumped together, all timers are eliminated (i.e.
anti-short, purge, ect.). This is mainly used for production
line testing however it may also be useful for field-testing as
well. The units are shipped with the “TEST” jumper on only
one of the pins. Please, do not leave a unit with the test
jumper in the test mode.
(Figure 2)
The LED Blink Codes Are As Listed In Below.
1 Blink Normal Operation
2 Blinks Compressor Lockout (ASCT)
3 Blinks Outdoor freeze condition
4 Blinks Indoor freeze condition
5 Blinks Simultaneous W & Y Call
Important Sensor Resistances
Are As Follows
77 °F - 10K ohms
50 °F - 19.9K ohms
35 °F - 30K ohms
30 °F - 34.4K ohms
Figure 2
TEST JUMPER POSITION FOR
NORMAL OPERATION
HEA
T PUMP
STRAIGHT COOL
STRAIGHT COOL/HEAT PUMP JUMER
Figure 1
