Bard Single Package Air Conditioners PA13421-A - Manual (Page 17)

Manual 2100-467
Page 17 of 23
HIGH PRESSURE SWITCH AND LOCKOUT
SEQUENCE (Standard Feature)
If the high pressure switch opens, the compressor
contactor will de-energize immediately. The lockout
timer will go into a soft lockout and stay in soft lockout
until the high pressure switch closes and the delay-on-
make time has expired. If the high pressure switch
opens again in this same operating cycle the unit will go
into manual lockout condition and the alarm circuit will
energize. Recycling the wall thermostat resets the
manual lockout.
LOW PRESSURE SWITCH, BYPASS, AND
LOCKOUT SEQUENCE (Standard Feature)
If the low pressure switch opens for more that 120
seconds, the compressor contactor will de-energize and
go into a soft lockout. Regardless the state of the low
pressure switch, the contactor will reenergize after the
delay-on-make time delay has expired. If the low
pressure switch remains open or opens again for longer
than 120 seconds the unit will go into manual lockout
condition and the alarm circuit will energize. Recycling
the wall thermostat resets the manual lockout.
ALARM OUTPUT
Alarm terminal is output connection for applications
where alarm signal is desired. This terminal is powered
whenever compressor is locked out due to HPC or LPC
sequences as described.
NOTE: Both high and low pressure switch controls are
inherently automatic reset devices. The high
pressure switch and low pressure switch cut out
and cut in settings are fixed by specific air
conditioner or heat pump unit model. The
lockout features, both soft and manual, are a
function of the Compressor Control Module.
ADJUSTMENTS
ADJUSTABLE DELAY-ON-MAKE AND
DELAY-ON-BREAK TIMER
The potentiometer is used to select Delay-on-Break time
from 30 seconds to 5 minutes. Delay-on-Make (DOM)
timing on power-up and after power interruptions is
equal to 2 minutes plus 10% of Delay-on-Break (DOB)
setting:
0.5 minute (30 seconds) DOB = 123 second DOM
1.0 minute (60 seconds) DOB = 126 second DOM
2.0 minute (120 seconds) DOB = 132 second DOM
3.0 minute (160 seconds) DOB = 138 second DOM
4.0 minute (240 seconds) DOB = 144 second DOM
5.0 minute (300 seconds) DOB = 150 second DOM
LOW AMBIENT CONTROL
Optional Low Ambient Control
An optional low ambient control is available for both
factory and field installed options. The low ambient
control is to be applied to the PA13 Series models when
operation below 55°outdoor conditions are anticipated.
Without this device, the evaporating pressure would fall
off, and the indoor coil would ice over.
The fan cycling control cycles the fan motor on, once the
liquid refrigerant pressure reaches 350 psig, and off, once
it has dropped to 225 psig. It will continue to cycle
between these parameters depending on outdoor
temperatures and the load/stage of the system.
This cycling maintains a minimum liquid pressure
affecting the minimum suction pressure. This effect
insures an evaporating temperature that is slightly above
the point of ice formation on the evaporator.
This field installed option is Bard Part #CMA-28. See
Figure 7.
FIGURE 7
LOW AMBIENT CONTROL WIRING