Routine Maintenance
CLCH-SVX009J-EN 69
Moisture Purge Cycle
By it’s very nature, any HVAC unit with a cooling coil serves
as a dehumidifier, reducing the surrounding air’s ability to
hold water vapor as its temperature falls. This normally
doesn’t present a problem when the unit is running.
However, when the fan stops, water vapor condenses on
the cold metal surfaces inside the air handler and remains
there until the air warms sufficiently to re-evaporate it.
This damp, dark environment—though temporary—can
encourage the growth of mold, mildew, and other
microbial contaminants.
Providing a moisture purge cycle 15 to 30 minutes after
shutdown disperses the cold, humid air inside the air-
handling system more evenly throughout the building.
This four-step cycle:
• Closes the outdoor air dampers.
• Turns off the cooling coil.
• Opens any variable-air-volume terminals connected to
the air handler.
• Operates the supply fan for 10 to 15 minutes.
Air movement discourages water condensation and
hastens re-evaporation of any condensate that does
happen to form. This simple preventative measure
effectively combats microbial growth and curbs moisture-
related deterioration of air-handling components.
Drain Pans
The condensate drain pan and drain line must be checked
to assure the condensate drains as designed. This
inspection should occur a minimum of every six months or
more often as dictated by operating experience.
If evidence of standing water or condensate overflow
exists, identify and remedy the cause immediately. Refer
to “Troubleshooting,” p. 74 for possible causes and
solutions.
To clean drain pans:
1. Disconnect all electrical power to the unit.
2. Wearing the appropriate personal protective
equipment, remove any standing water.
3. Scrape solid matter off of the drain pan.
4. Vacuum the drain pan with a vacuum device that uses
high-efficiency particulate arrestance (HEPA) filters
with a minimum efficiency of 99.97 percent at
0.3 micron particle size.
5. Thoroughly clean any contaminated area(s) with a
mild bleach and water solution or an EPA-approved
sanitizer specifically designed for HVAC use.
6. Immediately rinse the affected surfaces thoroughly
with fresh water and a fresh sponge to prevent
potential corrosion of metal surfaces.
7. Allow the unit to dry completely before putting it back
into service.
8. Be careful any contaminated material does not contact
other areas of the unit or building. Properly dispose of
all contaminated materials and cleaning solution.
Drive Motor and Pulley Replacement
1. Disconnect all electrical power.
2. Remove the belt from the pulley and temporarily
position it around the wheel rim.
3. Measure and record the distance from the inner edge
of the pulley to the mounting wall.
4. Loosen the set screw in the wheel drive pulley using an
Allen wrench and remove the pulley from the motor
drive shaft.
5. While supporting the weight of the drive motor in one
hand, loosen and remove the four mounting bolts.
6. Install a replacement motor with the hardware kit
supplied.
7. Install the pulley and adjust it to the distance recorded
in the previous step.
8. Tighten the set screw to the drive shaft.
9. Stretch the belt over the pulley and engage it in the
groove.
Low Limit Switch
In the event low limit switch (freeze stat) trips, the switch
will need to be reset manually. The low limit switch is
positioned on the air leaving face of the furthest
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.
WARNING
No Step Surface!
Failure to follow this recommendation could result
indeath or serious injury. Do not walk on the sheet
metal drain pan. Walking on the drain pan could cause
the supporting metal to collapse, resulting in the
operator/technician to fall.
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.
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