Manual 2100-356
Page 12
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance, wash the indoor coil
with a dish detergent.
CRANKCASE HEATERS
WH241 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 8 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
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 for constant air
circulation.
HEATING –
A 24V solenoid coil on reversing valve
controls heating cycle operation. Two thermostat options,
one allowing "Auto" changeover from cycle to cycle and the
other constantly energizing solenoid coil during heating
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 COMPRESSOR CRANK-
CASE:
1. MAKE CERTAIN THE ROOM THERMOSTAT IS IN
THE “OFF” POSITION. (THE COMPRESSOR 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 CRANK-
CASE.
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.
7961-061
FIGURE 8
season, and thus eliminating pressure equalization noise
except during defrost, are to be used. On "Auto" option a
circuit is completed from R-W1 and R-Y on each heating
"on" cycle, energizing reversing valve solenoid and pulling
in compressor contactor starting compressor and outdoor
motor. R-G also make starting indoor blower motor. Heat
pump heating cycle now in operation. The second option
has no "Auto" changeover position, but instead energizes
the reversing valve solenoid constantly whenever the system
switch on subbase is placed in "Heat" position, the "B"
terminal being constantly energized from R. A Thermostat
demand for heat completes R-Y circuit, pulling in
compressor contactor starting compressor and outdoor
motor. R-G also make starting indoor blower motor.
