Performing Routine Maintenance - Carrier 50ZH Manual To Operating And Maintaining

COOLING CYCLE
When operating in the cooling cycle, your heat pump will
run until the indoor temperature is lowered to the level you
have selected. On extremely hot days, your heat pump will
run for longer periods at a time and have shorter ''off''
periods than on moderate days.
The following are typical conditions that add extra heat and/or
humidity to your home. Your heat pump will work longer to
keep your home comfortable under these conditions:
• Entrance doors are frequently opened and closed
• Laundry appliances are being operated
• A shower is running
• More than the usual number of people are present in the
home
• More than the normal number of electric lights are in use
• Drapes are open on the sunny side of the home
HEATING CYCLE
With the SYSTEM switch of your indoor thermostat set to
the HEAT position, the heat pump will operate in its heating
mode until room temperature is raised to the level you have
selected. Of course, the heating unit will have to operate for
longer periods to maintain a comfortable environment on colder
days and nights than on moderate ones.
Defrost Cycle — When your heat pump is providing heat
to your home and the outdoor temperature drops below
45 degrees Fahrenheit, moisture may begin to freeze on the
surface of the outdoor coil. If allowed to build up, this ice
would impede airflow across the coil and reduce the amount
of heat absorbed from the outside air. So, to maintain energy-
efficient operation, your heat pump has an automatic defrost
cycle.
The defrost cycle starts at a preset time interval of 30 min-
utes. Defrost will start at the preset time only if the ice is
sufficient to interfere with normal heating operation.
After the ice is melted from the outdoor coil, or after a
maximum of 10 minutes in the Defrost mode, the unit will
automatically switch back to normal heating operation.
Do not be alarmed if steam or fog appears at the outdoor
unit during the defrost cycle. Water vapor from the melting
ice may condense into a mist in the cold outside air.
Emergency Heat — The EMERGENCY HEAT setting on
your thermostat refers to any supplementary heating
appliance that may be included in your home comfort sys-
tem. Operation of the EMERGENCY HEAT source may be
required if heating demands exceed the capacity of the heat
pump, or if the heat pump malfunctions.
The red light on your thermostat will glow if the EMER-
GENCY HEAT switch is moved from NORMAL to the EMER-
GENCY HEAT setting. This indicates that the heat pump is
off and the supplemental heating appliance is selected for
operation.
Also, if your particular model of heat pump includes a Serv-
ice Sentry™ circuit, the red light will glow if the compres-
sor malfunctions. Call your dealer for immediate service if
you suspect trouble.
The AUX HEAT red light will glow under normal operation
when the second stage of heat is operating.
During the heating season, switch to EMERGENCY HEAT
if the electricity to your outdoor unit is off for more than
30 minutes for any reason (i.e., power outage). Leave the
switch in the EMERGENCY HEAT position for an amount
of time equal to that during which the power was off. It is
not necessary to exceed 12 hours. If you cannot determine
how long the power has been off, leave the switch in the
EMERGENCY HEAT position for 8 hours.

PERFORMING ROUTINE MAINTENANCE

With the proper maintenance and care, your heat pump will
operate economically and dependably. Maintenance can be
accomplished easily by referring to the following directions.
However, before performing maintenance, consider these
important safety precautions:
• DISCONNECT ALL ELECTRICAL POWER TO THE
HEAT PUMP BEFORE REMOVING ACCESS PANELS TO
PERFORM SERVICE OR MAINTENANCE.
NOTE: THERE MAY BE MORE THAN ONE ELECTRI-
CAL DISCONNECT SWITCH.
• ALTHOUGH SPECIAL CARE HAS BEEN TAKEN
TO MINIMIZE SHARP EDGES IN THE CONSTRUC-
TION OF YOUR UNIT, BE EXTREMELY CAREFUL
WHEN HANDLING PARTS OR REACHING INTO THE
UNIT.
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