Manual 2100-277
Page 17
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.
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 WL482
and WL602 models covered by this manual and is optional
on the WL421 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.
