Component Operation and Maintenance
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7.2 Filters
Filters are usually the most neglected item in an environmental control system. To maintain efficient
operation, they should be checked monthly and changed as required. Because replacement intervals
vary with environmental condition and filter type, each unit is equipped with a filter clog switch. This
warns of restricted airflow through the filter compartment by activating the Change Filter alarm.
Turn power Off before replacing filters.
Liebert Challenger 3000 Liebert and Challenger ITR filters are 28-1/2" by 29-1/2", either 2" or 4"
thick, plus an optional 2" thick pre-filter. The filter is replaced from the front of the unit. On upflow
units, the filter is vertical, in front of the lower compartment. Pull the filter out toward you to remove
it. On downflow units, the filter is horizontal, above the electrical panel. Slide the filter out toward
you to remove it.
After replacing the filter(s), test the operation of the filter clog switch. Turn the adjusting screw coun-
ter clockwise to trip the switch — this will energize the Change Filter alarm. To adjust the switch pro-
ceed as follows: With the fan running, set the switch to energize the light with clean filters. The unit
panels must all be in place and closed to accurately find this point. Then turn the adjusting knob one
turn clockwise, or to the desired filter change point.
7.3 Blower Package
Periodic checks of the blower package include: belt, motor mounts, fan bearings, and impellers.
7.3.1 Fan Impellers and Bearings
Fan impellers should be periodically inspected and any debris removed. Check to see if they are
tightly mounted on the fan shaft. Rotate the impellers and make sure they do not rub against the fan
housing.
Bearings used on the units are permanently sealed and self-lubricating. They should be inspected for
signs of wear when the belt is adjusted. Shake the pulley and look for movement in the fan shaft. If
any excessive movement is noticed, bearings should be replaced. However, the cause of the wear must
be determined and corrected before returning the unit to operation.
7.3.2 Belt
The drive belt should be checked monthly for signs of wear and proper tension. Pressing in on belts
midway between the sheave and pulley should produce from 1/2" to 1" (12 to 25 mm) of movement.
Belts that are too tight can cause excessive bearing wear.
Belt tension can be adjusted by raising or lowering the fan motor base. Loosen nut above motor
mounting plate to remove belt. Turn nut below motor mounting plate to adjust belt tension. If belt
appears cracked or worn, it should be replaced with a matched belt (identically sized). With proper
care, a belt should last several years.
NOTICE
Risk of improper adjustment. Can cause equipment damage.
After adjusting or changing the belt, check to ensure that the motor base nuts are tightened.
The bottom adjustment nut should be finger tight. The top locking nut should be tightened
with a wrench.
