8
Heat Pump Start-Up Procedure
9. Check the cooling mode for the heat pump in
the same manner as above. The reversing valve
is energized when the thermostat is placed in
the cooling position. A clicking sound should be
noticeable from the reversing valve. By lowering the
temperature setting to call for cooling, the contractor
is energized. The compressor, blower and fan should
then be running. After the cooling mode is checked
out, turn the thermostat system switch to “OFF”.
10. Turn the thermostat system switch to “HEAT” and fan
switch to “AUTO”.
11. Slowly raise the heating temperature setting. When
the heating first stage makes contact, stop raising
the temperature setting. The compressor, blower and
fan should now be running with the reversing valve in
the de-energized (heating) position. After giving the
unit time to settle out, make sure the unit is supplying
heated air.
12. If the out door ambient is above 80°F, the unit may
trip on its high pressure cut out when on heating. The
compressor should stop. The heating cycle must be
thoroughly checked, so postpone the test to another
day when conditions are more suitable but - DO NOT
FAIL TO TEST.
If the out door ambient is low and the unit operates
properly on the heating cycle, you may check the
pressure cutout operation by blocking off the indoor
return air until the unit trips.
13. If unit operates properly in the heating cycle, raise
the temperature setting until the heating second
stage makes contact. Supplemental resistance
heat, if installed should now come on. Make sure it
operates properly.
NOTE:
If outdoor thermostats are installed the
outdoor ambient must be below the set point of
these thermostats for the heaters to operate. It may
be necessary to jumper these thermostats to check
heater operation if outdoor ambient is mild.
14. For thermostats with emergency heat switch, return
to step 11. The emergency heat switch is located
at the bottom of the thermostat. Move the switch to
emergency heat. The heat pump will stop, the blower
will continue to run, all heaters will come on and the
thermostat emergency heat light will come on.
15. If checking the unit in the wintertime, when the
outdoor coil is cold enough to actuate the defrost
control, observe at least one defrost cycle to make
sure the unit defrosts completely.
EVAPO
RAT
OR
COOLING
SERVIC E VALVE
SERVIC E PO RT
REVERSING VALVE
CO
ND
EN
SER
SERVIC E PO RT
CO MPR ESSOR
SERVIC E PO RT
AC CUM ULATO R
EXPANSION DEVIC E
CH ECK VALVE
OR IFICE
SERVIC E
VALVE
CH ECK VALVE
OR IFICE
INDO OR
CO IL
DISTRIBU TOR
OU TDO OR
CO IL
EVAPO
RAT
OR
HEATING
SERVIC E VALVE
SERVIC E PO RT
REVERSING VALVE
CO
ND
EN
SER
CO MPR ESSOR
SERVIC E PO RT
AC CUM ULATO R
CH ECK VALVE
OR IFICE
SERVIC E
VALVE
CH ECK VALVE
OR IFICE
INDO OR
CO IL
DISTRIBU TOR
OU TDO OR
CO IL
DISTRIBU TOR
Heat Pump Refrigerant Circuit - Figure 7
