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☐ Make sure that all retaining screws are reinstalled in the
unit access panels once these checks are complete.
☐ With the unit running, check and record the following:
–
ambient temperature
–
compressor oil level (each circuit)
–
compressor suction and discharge pressures (each
circuit)
–
superheat and subcooling (each circuit)
Record this data on an "operator's maintenance log" like
the one shown in
Table 78, p.
pressures indicate a refrigerant shortage, measure the
system superheat and system subcooling. For guidelines,
refer to
"Charging by Subcooling ," p.
Important: Do not release refrigerant to the atmosphere! If
adding or removing refrigerant is required, the
service technician must comply with all
federal, state and local laws. Refer to general
service bulletin MSCU-SB-1 (latest edition).
Heating Season
WARNING
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Verify that no power is
present with a voltmeter.
Before completing the following checks, turn the unit OFF
and lock the main power disconnect switch open.
☐ Inspect the unit air filters. If necessary, clean or replace
them.
☐ Check supply fan motor bearings; repair or replace the
motor as necessary. If the unit model number indicates
that the motor has an internal shaft ground, replace
with the same motor type.
☐ Check the fan shaft bearings for wear. Replace the
bearings as necessary. Lubricate the supply fan shaft
bearings with a lithium-based grease.
Note: These bearing are considered permanently
lubricated for normal operation. For severe dirty
applications, if relubrication becomes necessary,
use a lithium based grease. See
133
for recommended greases.
Important: The bearings are manufactured using a
special synthetic lithium-based grease
designed for long life and minimum relube
intervals. Over lubrication can be just as
harmful as not enough.
RT-SVX072D-EN
152. If the operating
116.
Table 68, p.
Service and Maintenance
☐ Use a hand grease gun to lubricate these bearings; add
grease until a light bead appears all around the seal.
Do not over lubricate!
☐ After greasing the bearings, check the setscrews to
ensure that the shaft is held securely. Make sure that all
bearing braces are tight.
☐ Inspect both the main unit control panel and heat
section control box for loose electrical components and
terminal connections, as well as damaged wire
insulation. Make any necessary repairs.
☐ Gas units only - Check the heat exchanger(s) for any
corrosion, cracks, or holes.
☐ Gas units only - Check the combustion air blower for
dirt or blockage from animals or insects. Clean as
necessary.
Note: Typically, it is not necessary to clean the gas
furnace. However, if cleaning does become
necessary, remove the burner inspection plate
from the back of the heat exchanger to access
the drum. Be sure to replace the existing
gaskets with new ones before reinstalling the
inspection plate.
☐ Check gas piping for leaks.
☐ Gas units only - Open the main gas valve and apply
power to the unit heating section; then initiate a "Heat"
test using the startup procedure described in
Furnace Startup," p.
118.
WARNING
Hazardous Gases and Flammable
Vapors!
Failure to observe the following instructions could
result in exposure to hazardous gases, fuel
substances, or substances from incomplete
combustion, which could result in death or
serious injury. The state of California has
determined that these substances may cause
cancer, birth defects, or other reproductive harm.
Improper installation, adjustment, alteration,
service or use of this product could cause
flammable mixtures or lead to excessive carbon
monoxide. To avoid hazardous gases and
flammable vapors follow proper installation and
setup of this product and all warnings as provided
in this manual.
Coil Cleaning
Regular coil maintenance, including annual cleaning
enhances the unit's operating efficiency by minimizing the
following:
•
Compressor head pressure and amperage draw
•
Water carryover
•
Fan brake horsepower
•
Static pressure losses
"Gas
149
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