Bard WA602 - Manual (Page 17)

Manual 2100-218
Page 15
Low Pressure Switch, Bypass, and Lockout
Sequence
If the low pressure switch opens for more than 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 relay circuit will energize.
Recycling the wall thermostat resets the manual lockout.
Alarm Relay Output
Alarm terminal is output connection for applications
where alarm relay is employed. 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 (180 seconds) DOB = 138 second DOM
4.0 minute (240 seconds) DOB = 144 second DOM
5.0 minute (300 seconds) DOB = 150 second DOM
During routine operation of the unit with no power
interruptions the compressor will operate on demand with
no delay.
SERVICE HINTS
1. Caution homeowner to maintain clean air filters at all
times. Also, not to needlessly close off supply and
return air registers. This reduces air flow through the
system, which shortens equipment service life as well
as increasing operating costs.
2. Switching to heating cycle at 75° F or higher outside
temperature may cause a nuisance trip of the remote
reset high pressure switch. Turn thermostat off then
on to reset the high pressure switch.
3. Check all power fuses or circuit breakers to be sure
they are the correct rating.
4. Periodic cleaning of the outdoor coil to permit full
and unrestricted airflow circulation is essential.
SEQUENCE OF OPERATION
COOLING – Circuit R-Y makes at thermostat pulling in
compressor contactor, starting the compressor and
outdoor motor. The G (indoor motor) circuit is
automatically completed on any call for cooling operation
or can be energized by manual fan switch on subbase of
constant air circulation. On all 230 volt units there is a
one minute off delay on the blower motor. 460 volt
models do not have an off delay. On a call for heating,
circuit R-W1 make at the thermostat pulling in heat
contact for the strip heat and blower operation. On a call
for second stage heat, R-W2 makes bringing on second
heat contactor, if so equipped.
COMPRESSOR CONTROL MODULE
The compressor control module is standard on the
WA482 and WA602 models covered by this manual and
is optional on the WA421 model. The compressor
control is an anti-short cycle/lockout timer with high and
low pressure switch monitoring and alarm relay output.
Adjustable Delay On Make And Break Timer
On initial power up or any time power is interrupted to
the unit the delay on make period begins which will be 2
minutes plus 10% of the delay on break setting. When
the delay on make is complete and the high pressure
switch (and low pressure switch if employed) is closed,
the compressor contactor is energized. Upon shutdown
the delay or break timer starts and prevents restart until
the delay on break and delay on make periods have
expired.
During routine operation of the unit with no power
interruptions the compressor will operate on demand with
no delay.
High Pressure Switch and Lockout Sequence
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
break 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 relay circuit will
energize. Recycling the wall thermostat resets the manual
lockout.