Table of Contents
Advertisement
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance, wash the indoor coil
with a dishwasher detergent.
SERVICE HINTS
1. Caution owner 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 operation costs.
2. The unit is equipped with a high pressure cut out
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.
HIGH & LOW PRESSURE SWITCH
The W12Aà models are supplied with a remote reset
high and low pressure switch. If tripped, this pressure
switch may be reset by turning the thermostat off then
back on again.
SEQUENCE OF OPERATION
HEATING – 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 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.
COMPRESSOR CONTROL MODULE
The compressor control module is optional on the
models covered by this manual. 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 on break time starts and prevents restart until
the delay on break and delay on make periods have
expired.
Manual 2100-509E
Page
14 of 17
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.
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
that 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.
Advertisement
Table of Contents
