Condenser Fan Operation; Service Hints; Sequence Of Operation; Compressor Control Module - Bard H24A2-A Manual

CONDENSER FAN OPERATION

NOTE: Certain models may be equipped with a
Low Ambient Control (LAC), and if so equipped the
condenser fan motor will have delay start until system
refrigerant operationg pressure builds up. After starting,
the fan motor may or may not cycle depending upon
ambient conditions. This is normal operation. The
condenser fan motor on 230/208 volt, one and three phase,
60 HZ units is a two-speed motor that comes factory
wired on high speed for peak performance. If ambient
conditions permit, it can be reconnected to low speed (red
wire) for lower sound level. See wiring diagram.

SERVICE HINTS

1. Caution owner/operator to maintain clean air
filters at all times. Also, not to needlessly close off
supply and return air registers. This reduces airflow
through the system, which shortens equipment
service life as well as increasing operating costs.
2. Check all power fuses or circuit breakers to be sure
they are the correct rating.
3. 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. (See Note under Condenser Fan
Operation if equipped with Low Ambient Control.)
The G (indoor motor) circuit is automatically
completed on any call for cooling operation or can be
energized by manual fan switch on subbase for constant
air circulation. 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 all models
covered by this manual. The compressor control module
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 anytime 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 is closed, the
compressor contactor is energized. Upon shutdown, the
delay on 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.
Manual 2100-585C
Page 16 of 22
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.
Low Pressure Switch, Bypass & 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 the 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 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)
1.0 minute (60 seconds)
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.
Typical Settings for Dual Unit Installation:
Unit 1: DOB set at 2 minutes, and DOM is 132 seconds
Unit 2: DOB set at 4 minutes, and DOM is 144 seconds

PRESSURE SERVICE PORTS

High & low pressure service ports are installed on all units
so that the system operating pressures can be observed. A
pressure table can be found later in the manual covering all
models. It is imperative to match the correct pressure table
to the unit by model number. See Table 2.
DOB = 123 second DOM
DOB = 126 second DOM