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Service Maintenance
Service maintenance should be performed by qualified service
personnel.
Cooling Season
To keep the unit operating safely and efficiently, the manufacturer
recommends that a qualified service technician check the entire
system at least once each season or more often if needed. The
service technician should examine these areas of the 4YCZ6 unit:
filters (for cleaning or replacement)
●
motors and drive system components (for proper operation)
●
economizer gaskets (for possible replacement)
●
safety controls (for mechanical cleaning)
●
electrical components and wiring (for possible replacement
●
and connection tightness)
condensate drain (for proper sealing and cleaning)
●
unit duct connections (to see that they are physically sound
●
and sealed to the unit casing)
unit mounting support (for structural integrity)
●
the unit (for obvious unit deterioration)
●
Heating Season
Complete the following unit inspections and service routines
described at the beginning of each heating season.
Visually inspect the unit to ensure that the airflow required
●
for combustion and condenser coil is not obstructed from the
unit.
Inspect the control panel wiring to verify that all electrical
●
connections are tight and that the wire insulation is intact.
Check the operation of the gas ignition system as follows:
●
Turn off the gas supply with the unit operating to verify that
the gas valve closes and that a re-ignition cycle is initiated
by the unit.
Visually inspect the inside of the burners and the burner ports
●
for deposit buildup and corrosion. Wipe and brush the inside
of the burner and the burner ports and then clean with a dry
cloth. If the deposit buildup or corrosion is excessive, replace
the burners.
Installer's Guide
Manifold Pressure Check and Adjust
1. Connect a manometer to the pressure tap at the outlet side
of the unit's gas valve (remove the Control/Heat access
panel). Read the manifold pressure with the burners firing.
See Figure 16 on page 17 for gas valve connections.
2. If the manifold pressure reading does not match the value
indicated on the unit's nameplate, the unit's pressure regula-
tor must be adjusted as follows:
a. Remove the cover screw on the gas regulator located on
the front side of the unit's gas valve.
b. Turn the adjusting screw clockwise to increase manifold
pressure or counterclockwise to decrease manifold pres-
sure.
3. Check the temperature rise during furnace operation to insure
that it falls within the range specified on the unit's nameplate.
4. If the temperature rise noted is outside of the specified limits,
adjust the indoor air flow to cause the temperature rise of
the heat exchanger to fall within the required range.
Flue Hood and Combustion Blower Cleaning
▲
!
Never use combustible cleaning fluids on any part of the
furnace.
Before each heating season, the Flue Hood and combustion
blower should be inspected for signs of any blockage or soot-
ing. Any cleaning required should be performed only by a
qualified service technician using the following procedure:
1. Turn the comfort control to OFF. Turn off power to the unit.
Turn the main power disconnect OFF. Turn the manual gas
valve OFF.
2. Remove the Flue Hood from the side panel.
3. Remove the combustion blower from the vestibule panel.
Disconnect blower wiring and pressure switch hose.
4. Wipe blower and Flue Hood clean with a dry cloth.
5. Replace the combustion blower gasket with a new one.
6. Reassemble combustion blower and Flue Hood in reverse
order of removal. Reconnect pressure switch hose.
7. Verify all wiring is correct per the unit's wiring diagram.
8. Follow start-up procedure to place unit back in service. Verify
proper operation.
CAUTION
Page 25
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