Manual 2100-441
Page 13
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance, wash the indoor
coil with a dish detergent.
CRANKCASE HEATERS
WH243 units are provided with compressor crankcase
heat.
These models have an insertion well-type heater located
in the lower section of the compressor housing. This is
a self-regulating type heater that draws only enough
power to maintain the compressor at a safe temperature.
Some form of crankcase heat is essential to prevent
liquid refrigerant from migrating to the compressor
causing oil pump out on compressor start up and
possible valve failure.
The decal in Figure 9 is affixed to all outdoor units
detailing start up procedure. This is very important.
Please read carefully.
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. The heat pump wall thermostats perform multiple
functions. Be sure that all function switches are
correctly set for the desired operating mode before
trying to diagnose any reported service problems.
4. Check all power fuses or circuit breakers to be sure
they are the correct rating.
5. Periodic cleaning of the outdoor coil to permit full
and unrestricted airflow circulation is essential.
SEQUENCE OF OPERATION
OCCUPIED MODE
VENTILATION SEQUENCE
– The ERV and indoor
blower will be continuously energized when the A1
terminal is energized.
IMPORTANT
THESE PROCEDURES MUST BE
FOLLOWED AT INITIAL START UP
AND AT ANY TIME POWER HAS
BEEN REMOVED FOR 12 HOURS
OR LONGER.
TO PREVENT COMPRESSOR DAMAGE
WHICH MAY RESULT FROM THE PRESENCE
OF LIQUID REFRIGERANT IN THE COM-
PRESSOR CRANKCASE:
1. MAKE CERTAIN THE ROOM THERMOSTAT
IS IN THE “OFF” POSITION. (THE COM-
PRESSOR IS NOT TO OPERATE.)
2. APPLY POWER BY CLOSING THE SYSTEM
DISCONNECT SWITCH. THIS ENERGIZES
THE COMPRESSOR HEATER WHICH
EVAPORATES THE LIQUID REFRIGERANT
IN THE CRANKCASE.
3. ALLOW 4 HOURS OR 60 MINUTES PER
POUND OF REFRIGERANT IN THE SYSTEM
AS NOTED ON THE UNIT RATING PLATE,
WHICHEVER IS GREATER.
4. AFTER PROPERLY ELAPSED TIME THE
THERMOSTAT MAY BE SET TO OPERATE
THE COMPRESSOR.
5. EXCEPT AS REQUIRED FOR SAFETY
WHILE SERVICING — DO NOT OPEN
SYSTEM DISCONNECT SWITCH.
FIGURE 9
START UP LABEL
7961-061
COOLING SEQUENCE
– On a call for cooling, the
compressor of the unit is energized to provide cooling.
A call for cooling cancels dehumidification mode.
Cooling mode is only available when the timer is
energized.
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.
