Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 16)

MAMM-VHC-IOM-1A (JANUARY 2013) 16
4. Using a steam cleaning machine, clean the leaving
airside of the coil first (going downward) then clean the
entering airside. Use a block-off to prevent the steam
from penetrating a dry section of the unit.
5. Allow the unit to dry thoroughly before restoring power.
6. Damaged coil fins (excluding brazed aluminum)
should be straightened by using a fin comb.
7. Close all panels and doors once the coil is dry.
8. Restore electrical power to the unit.
WARNING
Disconnect the main power switch to the unit before per-
forming service and maintenance procedures.
!
Disconnect the four-wire service connector from the
motor (#1, Figure 5). Loosen the four bolts (#2, Figure
5) and all screws that fasten the blower to the flex collar.
Slide the fan assembly out of the unit. The fan assembly
may have to be lifted over the fan assembly plate bolts
(#3, Figure 5).
The belt tension is adjusted by the positioning of the ro-
tating motor base plate. Loosen the two adjustment bolts
(#4, Figure 5) on the base plate. Rotate the motor and
base plate to achieve the maximum belt deflection as
described under belt tension adjustment below. Tighten
the adjustment bolts (#4, Figure 5). Verify that the
sheave and pulley faces are still parallel. The fan rpm
can be adjusted to achieve the design airflow by setting
the adjustable sheave on the motor shaft. The pulley set
screw torque setting is 110 in.-lbs to 130 in.-lbs.
Motor and Blower Removal – Down, Side and End Supply/Exhaust
Motor and Blower Service – Down, Side and End Supply/Exhaust
Figure 5: Motor and blower orientation for down, side and
end supply/exhaust options
After disconnecting the power from the unit, determine
if the actuator is defective. Disconnect the 24 volt power
source. Connect the actuator directly to a 24 volt power
source with an appropriate cable. If the damper operates
correctly, the problem is either in the wiring connections
or main circuit board.
If the actuator does not work, it must be replaced. Loosen
the nuts on the jack shaft clamp and remove the actua-
tor. Tighten the clamp on the damper jack shaft. Test for
proper operation.
Testing and Replacement of the Damper Actuator